Hierarchically Ordered Nanochannel Array Membrane Reactor with

Subscriber access provided by EKU Libraries

Letter

Hierarchically Ordered Nanochannel Array Membrane Reactor With Three Dimensional Electrocatalytic Interfaces for Electrohydrogenation of CO2 to Alcohol Xinyi Zhang, Bingmei Huang, Chenghua Sun, Wei Lu, Zhiqun Tian, Pei Kang Shen, Huanting Wang, Dongyuan Zhao, and Douglas R. MacFarlane ACS Energy Lett., Just Accepted Manuscript • DOI: 10.1021/acsenergylett.8b01521 • Publication Date (Web): 01 Oct 2018 Downloaded from http://pubs.acs.org on October 3, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

Hierarchically Ordered Nanochannel Array Membrane Reactor with Three Dimensional Electrocatalytic Interfaces for Electrohydrogenation of CO2 to Alcohol Xinyi Zhanga,b* ,Bingmei Huang a, Chenghua Sun b, Wei Lu c, Zhi Qun Tian a, Pei Kang Shen a, Huanting Wang d, Dongyuan Zhao d, Douglas R. Macfarlane b* a

Collaborative Innovation Centre for Sustainable Energy Materials; Guangxi Key Laboratory of Electrochemical Energy Materials, Guangxi University, Nanning, 530004, China. b

ARC Centre of Excellence for Electromaterials Science, School of Chemistry, Monash University, Victoria 3800, Australia.

c

University Research Facility in Materials Characterization and Device Fabrication, The Hong Kong Polytechnic University, Hong Kong, China. d

Department of Chemical Engineering, Monash University, Victoria 3800, Australia

*Corresponding Author E-mail address: [email protected]; [email protected]

1 Environment ACS Paragon Plus

ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ABSTRACT The electrochemical conversion of CO2 into liquid fuels offers alternative ways to produce renewable fuels and store the surplus renewable energy. However, significant chemistry challenges still remain, particularly in relation to the kinetic inertness of CO2 and thermodynamic complexity of the multiple electron transfer processes involved. We describe a new type of flow-through membrane reactor, based on hierarchically-ordered platinum nanochannel array with macropore channels in combination with mesoporous walls. The membrane reactor exhibits unique three dimensional electrocatalytic interfaces with high activity and selectivity in CO2 conversion producing methanol and ethanol as the dominant liquid products. The Faradaic efficiency and yield for alcohol production are up to 23.9 % and 2.1×10-8 mol s-1 cm-2 at 51mA/cm-2, respectively. Experimental and density functional theory studies evidence that substantial (110) facets and a high density of atomic surface steps contribute significantly to the intrinsic activity and selectivity for conversion of CO2 to alcohol.

TOC GRAPHICS


Page 2 of 21

Page 3 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

Limited fossil fuel resources and increasing CO2 emissions are two of the most serious problems facing us in the 21st century.1 Conversion of CO2 to transportable fuels using renewable energy sources offers a promising approach to a carbon neutral cycle.2 Electrochemical CO2 reduction has been the subject of intense investigation because it can operate at ambient conditions and be coupled to energy sources such as wind, hydro or solar.3-5 So far, various catalysts including metals and alloys,6,7 metal organic frameworks,8 molecule metal complexs,9 and ionic liquids10,11 have been explored. More recently, much interest has centered on the effects of nanostructures,12,13 From a practical point of view, easily transportable liquid fuel products, especially alcohols, are highly desirable. However, the most commonly obtained products of CO2 conversion are CO and formate. The conversion of CO2 to alcohol involves multiple proton-electron transfer processes, and the development of electrocatalysts with high activity as well as favorable binding energy to intermediates is the key to achieving this goal.14 In electrochemical conversion of CO2, the release of CO from the electrode surface or further reduction of CO is the critical step.15,16 According to the Sabatier principle, optimum catalysts should bind atoms and molecules with an intermediate strength, which allows the adsorption and activation of the reactants and dissociation of the products. As a well-known catalyst, platinum is nonetheless not usually considered as an ideal electrocatalyst for CO2 conversion due to its strong CO adsorption, producing inactivation of the surface; it also has high activity for hydrogen evolution, which is the main competing reaction in electrochemical CO2 reduction. On the other hand, a catalyst surface with relatively stable bond to CO is desirable in order to accomplish the multi-electron reaction and the generated surface bound hydrogen could be a source of a CO2 hydrogenation reaction. Many studies have shown that the catalytic properties



of Pt can be significantly improved through nanoengineering its surface structure and morphology.17-22 Electrochemical CO2 reduction to formic acid with high faradaic efficiency has been achieved on carbon-supported Pt alloy nanoparticles.23 Long carbon chain organic molecules, such as iso-propanol and C≥4 oxygenates have also been synthesized by using Pt nanoparticles on carbon-based electrodes; unfortunately, the supported Pt nanoparticles show low selectivity and impractically low yield.24,25 In this work, we present a different approach to a flow-through membrane reactor based on hierarchically-ordered Pt nanochannel array (HPNA). The HPNA provides three dimensional electrocatalytic sites for CO2 adsorption and reduction and enables high-efficient and high-yield production of alcohol. The HPNAs were fabricated through a dual-templating approach utilizing reverse, porous poly(methyl methacrylate) as a hard template and nonionic surfactant octaethylene glycol monohexadecyl ether as a lyotropic liquid crystal (LLC) precursor. The scanning electron micrograph (SEM), transmission electron micrograph (TEM) and scanning transmission electron micrograph (STEM) images and XRD pattern are shown in Figure 1 and Figure S1, S2. The HPNA possesses a uniform, hexagonal-arranged array of macropores with thickness and pore diameter about 10µm and 250 nm, respectively (Figure1a,b). The top and cross-sectional TEM images show that the HPNA consists of uniformly distributed mesopores with pore size of ~2-3 nm (Figure1c-e) templated by the nonionic surfactant liquid crystal. The high resolution TEM (HRTEM) images of the mesoporous wall are shown in Figure1f and Figure S3. Interestingly, a large number of single crystalline domains with (110) facets are observed on the mesoporous Pt surface despite the polycrystalline nature of the HPNA. Figure 1g exhibits the small angle X-ray diffraction pattern of HPNA, showing a well-defined mesostructure. The HPNA shows


Page 4 of 21

Page 5 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

uniform mesopores with porosity and pore size about 32.5% and 2.5 nm, respectively (Figure 1h,i).

Figure 1. Material characterization of the HPNA reactor. (a) Schematic illustration and (b) SEM image of the HPNA reactor. (c) TEM image of a macropore on the HPNA and the corresponding electron diffraction pattern (inset). TEM images of a cross-sectional view (d) and an enlarged cross-sectional view (e). (f) HRTEM image and the corresponding Fourier transform (FT) pattern (inset). (g) Small angle XRD pattern, (h) N2 sorption isotherm, and (i) pore size distribution of HPNA. The setup for electrohydrogenation is shown in Figure 2a. CO2 gas was continuously bubbled from the backside of the flow-through HPNA reactor. The electrochemical conversion of CO2 was carried out in 1M Na2CO3 solution for 1 hour by a potentiostatic method. Liquid products were determined by 1H nuclear magnetic resonance (NMR).



The results showed that methanol and ethanol were the dominant liquid products in the potential range measured (Figure 2b,c). The methanol formation is first observable at 0.63 V (vs RHE), exhibiting a high activity for reduction of CO2 to methanol.26,27 The main liquid product is methanol and an increasing fraction of ethanol, acetate and acetone is produced beyond -1.05 V (vs RHE). Their yield increases with increasing negative potential. The Faradaic efficiency reaches above 15.26%, 6.48% and 25.12 % for methanol, ethanol and total liquid products at -1.75V (vs RHE). At -2.05 V (vs RHE), the

Figure 2. Electrochemical conversion of CO2 using HPNA as a flow-through membrane reactor. (a) Schematic diagram of the cell: 1. Spacer, 2. stainless steel mesh support, 3. HPNA


Page 6 of 21

Page 7 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

reactor, 4. reference electrode, 5. Nafion membrane, and 6. counter electrode. Reduction potential-dependent faradaic efficiency (b) and yield (c) for CO2 reduction. (d) Total carbon products and hydrogen yield as a function of potential.

HPNA reactor gives rise to the production of alcohol (methanol and ethanol) and total liquid fuels with yields of 2.1 ×10-8 mol s-1 cm-2 and 2.38 ×10-8 mol s-1 cm-2, and the corresponding Faradaic efficiencies for methanol, ethanol and total liquid products are about 15.39%, 8.52% and 28.11%, respectively. A decline in Faradaic efficiency occurs as the potential is further increased in the negative direction. The yield of total carbon product increases with the CO2 flow rate and reaches a maxmium at 2.4 ml/cm2.min (Figure S4). The yield of alcohol decreases under higher CO2 flow rate may be because that the CO2 gas displaces the electrolyte away from the internal wall of the nanochannels. With the advantages of three-dimensional macrochannel interface and large mesoporous active surface area, the HPNA reactor exhibits excellent performance in terms of Faradaic efficiency and yield for alcohol production compared to those in previous reports, as summarised in Supplementary Table S1. The electrochemical stability of HPNA was investigated by chronoamperometry; the HPNA produces current densities of approximately 51 mA/cm2, and no obvious decay in the current density occurred at -2.05 V (vs RHE) over 10 hours of testing (Figure S5). The possible product contributions from the contamination of the residual PMMA or the organic surfactant were determined by a series of control experiments. First, an experiment was performed to confirm that the source of the carbon in the products was the bubbled CO2, by using Ar to replace CO2 in the experiment; no methanol was detected. Second, to demonstrate the catalytic activity of nanostructured Pt, Pt nanowires were utilized as the electrocatalyst. As shown 7 Environment ACS Paragon Plus


in the Figure S6, methanol was obtained at -1.05 V (vs RHE), and both methanol and ethanol were produced at -1.6 V (vs RHE). In addition, the yield of total carbon product depends on the CO2 flow rate, which also evidences that the source of carbon products is from the bubbled CO2. The gas-phase products were collected from the cathode compartment and analyzed by GC. H2 is detected as exclusive gas-phase product, and no CH4 or CO can be detected. Figure 2d shows the total carbon products and hydrogen yield as a function of potential. It can be seen that H2 is the dominant product at all applied potentials. In the initial stage, hydrogen is the only product and no carbon products are detected at low overpotential. With the increase of overpotential, the liquid carbon products increase along with the dominant hydrogen. The yield of hydrogen increases with the increase of overpotential, but the corresponding Faradaic efficiency decreases (Figure S7), as a result of the competition between hydrogen evolution and the CO2 reduction reactions. Electrochemical characterization was carried out on the HPNA reactor to further explore the reaction mechanism. As shown in the linear sweep voltammetric (LSV) curves, the HPNA exhibits much less negative onset potential and much higher current in comparison with Pt foil in 1M Na2CO3 in the presence of both Ar and CO2 ( Figure 3a). The current densities on HPNA are very similar in both Ar and CO2. This indicates similar charge transfer rates in the CO2 and H2 reduction pathways. A small shoulder appears at 0.2 V (vs RHE) on the HPNA, and the current decreases a little which can be ascribed to the suppression of hydrogen evolution in the presence of CO2.28 Anodic stripping voltammetry was used to study the adsorption and reduction of CO2 in the initial stages of the process. The initial chronopotentiometric curves at different reductive current densities are shown in Figure 3b. At -5 mA/cm2, the initial potential


Page 8 of 21

Page 9 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

shifts rapidly to negative potential, which corresponds to the charge-transfer-limited process. The feature appears at about 0V (vs RHE) may correspond to the hydrogen evolution and formation of COad. Diffusion-controlled reaction kinetics is expected due to the extremely large surface area of the HPNA reactor. After the initial transition period, the potential reaches a steady state at -0.25 V

Figure 3. Electrochemical characterization of HPNA. (a) Linear sweep voltammetric curves on the HPNA in 1M Na2CO3 with bubbling CO2 or Ar with a scan rate of 20 mV/s. (b) Chronopotentiograms at different current densities for 200 sec. (c) Subsequent anodic stripping voltammograms on HPNA and Pt foil (inset) in 0.5 M H2SO4 with a scan rate of 20 mV/s. (d) Cyclic voltammograms on HPPM in 0.5 M H2SO4 with a scan rate of 20 mV/s. (vs RHE). The higher is the current density used, the shorter the period required to reach a steady state. Figure 3c exhibits the subsequent anodic stripping voltammograms on the HPNA



reactor. The anodic peak at about 0.63 V (vs RHE) on HPNA corresponds to the oxidation of the COad intermediate, which has been well demonstrated by Fourier transform infrared spectroscopy (FTIR).29 The corresponding curve for Pt foil (after -5mA/cm2 reduction step) is shown in the inset of Figure 3c; the onset of oxidation on HPNA is about 0.2 V lower than that on Pt foil. This shift of onset potential reveals a remarkable enhancement in the electrochemical kinetics, as will be discussed further below. The intensity and area of the anodic peak on HPNA are significantly higher than those on Pt foil due to the larger amount of COad on the HPNA surface. This directly evidences the high CO2 adsorption capacity of the HPNA reactor. The anodic peak positions and areas at different current densities are almost the same, suggesting similar COad adsorption under these conditions. As can be determined from the cyclic voltammograms on the HPNA with and without the presence of CO2, the corresponding electrochemically active surface area of the electrode decreased at the presence of CO2 (Figure 3d). This difference is caused by the involvement of formation and adsorption of CO, which is confirmed by the subsequent CO oxidation peak at the anodic region. In the absence of CO2, both Hupd1 and Hupd2 peaks appeared, while the latter, the strong adsorbed hydrogen, disappeared in the presence of CO2, revealing the interaction between the adsorbed CO species and hydrogen weakens the H-Pt surface bond and decreases the H adsorption stability. Insight on the surface atomic structure is important for understanding the reaction mechanism and optimizing the performance. As shown in scanning TEM (STEM) and HRTEM images (Figure 4a,b), the surface of the HPNA contains uniformly distributed mesopores whilst the edges of the macropores are rather rough, resulting in a number of protrusions with the shapes close to truncated polyhedrons. Representative HRTEM images and the corresponding FT patterns of three protrusions clearly exhibit the surface atomic structures (Figure 4c). It is


Page 10 of 21

Page 11 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

worth noting that all the three protrusions exhibit (110) facets, and certain atomic steps and high-index facets, including {113} and {331} can also be observed. The atomic steps on the corresponding high-index facets are illustrated in Figure 4d. Figure 4e shows the cross-section image of the HPNA

Figure 4. Surface crystallographic structures of HPNA. (a) STEM and (b) HRTEM images of the edge of a macropore. (c) HRTEM images of selected regions indicated in b and the corresponding FT patterns (insets). (d) Schematic illustration of (113) and (331) facets. (e) HRTEM image of cross-sectional view of the mesopore channels. obtained by an ion milling method. The mesochannels are indicated by red arrows, which are almost perpendicular to the wall surface, revealing the alignment of the liquid crystal template. The top of the mesochannels have shapes that are very close to the aforementioned protrusions, exhibiting similar surface atomic structure. These atomic steps can play a significant role in enhancing the electrochemical reaction kinetics of CO2 reduction.30 The surfaces with higher step density have higher rates of CO2 reduction. The high density of low-coordination atoms on



the topmost surface can act as the catalytically active sites for the adsorption and reduction of CO2 since they interact more strongly with molecules owing to their modified local electronic structure. It is expected that localized electrical fields originating from steps produce local surface potential differences.31 This leads to reduced reaction barriers compared to a closepacked surface. The density and activity of atomic steps are different on different facets and it is known that Pt(311), Pt(331) and Pt(110) have high step densities.32 Among them, Pt(110) is of particular interest due to its high activity in CO2 reduction, which is even higher than some high index surfaces, such as Pt(332) and Pt(997).32 In addition, the energy barrier for the hydrogen evolution reaction on Pt(110) is larger than that on Pt(111), enhancing the selectivity of the former towards CO2 reduction.33 Our electrochemical measurement also revealed that the Pt(110) facets on the HPNA can effectively suppress the hydrogen evolution kinetics and achieve both high selectivity and activity for CO2 conversion. Both XRD and TEM analysis reveals that HPNA is composed of many small nanograins and grain boundaries. Grain boundaries have been proved to be enhanced active sites for electrochemical reduction of CO2.34 This should also contribute to the electrocatalytic activities. The in situ FTIR spectra of the HPNA reactor at -2.05 V (vs RHE) after different reaction time were measured in CO2 saturated solution. The intensity of the bands increase the reaction time and reach a steady state after 10 minutes, indicating a maximum coverage of CO species on the Pt surface (Figure S8). A broad band at 2000-2150 cm-1 can be observed, corresponding to CO adsorption on Pt.35-37 After multipeak fitting, three infrared absorption bands at about 2050, 2082 and 2120 cm-1 are obtained, indicating that three CO species present on the HPNA. The 2050 cm-1 band can be assigned to linear adsorbed CO atop species in the vicinity of steps and kinks,35.36 which have been observed at the mesopore edges as shown in Figure 4. The


Page 12 of 21

Page 13 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

2080 cm-1 bands can be attributed to linear CO adsorbed at terrace sites.37 The high frequency band at 2120 cm-1 can be interpreted as CO adsorbed on reconstructed Pt surface.38 That may be related to the substantial Pt(110) facets of HPNA，which are composed of (110) steps and (111) terraces and can be reconstructed to form a [3(111) × 2(111)] structure to decrease the surface energy.30 The CO hydrogenation reaction is regioselective. The relative preference of CO to reduce to CHOad or COHad is a critical for the final products. It is estimated that the preference of CHO formation from CO results in the selectivity to methanol over methane.15 The product selectivity depends on both binding energies of CO and OH. Pt has a strong binding affinity for CO but a weak oxygen binding, which may favor leaving the C-O bond intact during the reaction, leading to methanol instead of methane.39 In order to determine the radical intermediate of COad reduction, the hydrogenation of CO2 has been investigated on Pt(110) and Pt(111) by DFT calculations, and the energy profiles is shown in Figure S9. The formation of adsorbed atomic hydrogen is an exothermic process, with ∆G= -2.42 eV and -2.44 eV for the formation of two Had-atoms through the Volmer step (H+ + e- → Had) on Pt(110) and Pt(111), respectively, indicating that those surfaces are actually covered with large amount of Had under the electrochemical conditions. The first hydrogenation reaction is the ratedetermining step with ∆G= 1.02 eV and 2.17 eV for Pt(110) and Pt(111), respectively. So a large amount of Pt(110) should be the key reason why HPNA offers much low overpotential for CO2 conversion. Based on our calculations, CHOad is preferable than COHad on Pt(110). The energy input for COad → CHOad is 0.67 eV and 1.74 eV for Pt(110) and Pt(111), respectively. This further confirms the key role of Pt(110) in the formation of alcohol. The CO binding energy can be adjusted by the surface structure. The anodic stripping voltammograms showed that the onset oxidation potential of COad on HPNA is about 0.2 V less than that on Pt foil,



Page 14 of 21

revealing a significant decrease of the CO binding strength hence the reaction energy barrier. As illustrated in Figure S10, due to the decrease of the CO binding strength, the energy barrier for COad → HCOad becomes lower than that for COad → COHad, this may not only favor the pathway toward methanol, but also effectively reduces the limiting overpotential for the CO2 reduction. In the conventional electrochemical process, the low solubility of CO2 leads to low limitation of the mass transport and charge transfer. The hole-through nanochannels of HPNA allow access to CO2 gas and an efficient mass transport through the porous structures is enabled. The continuous flow of CO2 gas inside the nanoochannels of HPNA reactor increases the partial pressure of CO2 gas as well as enhances the mass transfer on the three-phase interfaces, which is beneficial for the CO2 reduction in the competition with hydrogen evolution as well as the kinetics of C-C coupling. Importantly, the large mesoporous surface allows sufficient adsorption of CO2, enhancing the active surface area. The high capacity of CO2 adsorption creates favorable circumstance for the C–C coupling. COad → CHOad is energetically preferred on Pt (110) surface, which also contribute to the formation of C−C bonds.40 Moreover, the high aspect ratio (~40) of macrochannels in HPNA confines the diffusion of the reaction products and favors their consecutive reaction (such as CH3OH + COad + 4Had → CH3CH2OH + H2O) inside the reactor. The more negative of applied potential, the more highly protonated intermediate species are produced on the Pt surface and faster kinetics for C-C and even C-C-C coupling is favored. So the yield of ethanol, acetate and acetone increases at more negative potentials. In conclusion, we have developed a novel flow-through membrane reactor based on a hierarchically-ordered

platinum

nanochannel

array

capable


of

highly

efficient

Page 15 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

electrohydrogenation of CO2 to alcohol at ambient conditions. The superior performance results from the three dimensional architecture, in which the macrochannel arrays enable efficient mass transfer to and from the interfaces, while the mesoporous walls provide a large number of highly catalytic active sites for CO2 adsorption and reduction. This fabrication method is not inherently area limited and can be easily scaled up. Hence we hope that our work may open a new avenue towards the practical utilization of CO2 for large-scale production of liquid fuels. ASSOCIATED CONTENT

Supporting

Information.

measurement

and

products

Experimental, analysis,

materials

computational

characterizations, details,

electrochemical

Supplementary

figures,

Supplementary table.

AUTHOR INFORMATION Email address: [email protected]; [email protected]. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT This work was supported by the National Basic Research Program of China (2015CB932304), the Australian Research Council through Grant No.: DP120104334. D. R. M is grateful to Australian research Council for the Laureate Fellowship.

REFERENCES 15 Environment ACS Paragon Plus


(1)

Davis, S. J. ; Caldeira, K.; Matthews, H. D. Future CO2 Emissions and Climate

Change from Existing Energy Infrastructure. Science 2010, 329, 1330-1333. (2) Kondratenko, E.V.; Mul, G.; Baltrusaitis, J. ; Larrazabal, G. O. ; Perez-Ramirez, J. Status and Perspectives of CO2 Conversion into Fuels and Chemicals by Catalytic, Photocatalytic and Electrocatalytic Processes. Energ. Environ. Sci. 2013, 6, 3112-3135. (3) Li，H., Opgenorth, P. H., Wernick, D. G., Rogers, S., Wu, T.-Y., Higashide, W., Malati, P., Huo, Y.-X., Cho, K. M., Liao, J. C., Integrated Electromicrobial Conversion of CO2 to Higher Alcohols, Science, 2012, 335, 1596-1596. (4) Vasileff, A.; Zheng, Y., Qiao, S. Z. Carbon Solving Carbon’s Problems: Recent Progress of Nanostructured Carbon-Based Catalysts for the Electrochemical Reduction of CO2. Adv. Energy Mater. 2017, 7, 1700759. (5) Jiao, Y.; Zheng, Y.; Chen, P.; Jaroniec, M.; Qiao, S. Z. Molecular Scaffolding Strategy with Synergistic Active Centers To Facilitate Electrocatalytic CO2 Reduction to Hydrocarbon/Alcohol. J. Am. Chem. Soc. 2017, 139, 18093-18100. (6) Hori, Y. Electrochemical CO2 Reduction on Metal Electrodes. In Modern Aspects of Electrochemistry, No 42, Springer, New York, NY 2008. (7) Ma, M.; Liu K.; Shen, J.; Kas R.; Smith W. A. In Situ Fabrication and Reactivation of Highly Selective and Stable Ag Catalysts for Electrochemical CO2 Conversion. ACS Energy Lett. 2018, 3, 1301-1306. (8) Hod, I.; Sampson, M. D.; Deria, P.; Kubiak, C. P.; Farha, O. K.; Hupp, J. T.. FePorphyrin-Based Metal-Organic Framework Films as High-Surface Concentration,


Page 16 of 21

Page 17 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

Heterogeneous Catalysts for Electrochemical Reduction of CO2. ACS Catal. 2015, 5. 6302-6309. (9) Angamuthu, R.; Byers, P.; Lutz, M.; Spek, A. L.; Bouwman, E. Electrocatalytic CO2 Conversion to Oxalate by a Copper Complex. Science 2010, 327, 313-315. (10) Rosen, B. A.; Salehi-Khojin, A.; Thorson, M. R.; Zhu,W.; Whipple, D. T.; Kenis, P. J. A.; Masel, R. I. Ionic Liquid-mediated Selective Conversion of CO2 to CO at Low Overpotentials. Science 2011, 334, 643-644. (11) Sun, X. F.; Zhu, Q. G.; Kang, X. C.; Liu, H. Z.; Qian, Q. L.; Zhang, Z. F.; Han, B. X. Molybdenum-bismuth Bimetallic Chalcogenide Nanosheets for Highly Efficient Electrocatalytic Reduction of Carbon Dioxide to Methanol. Angew. Chem. Int. Ed. 2016, 55, 6771-6775. (12) Gao, S.; Lin, Y.; Jiao, X. C.; Sun,Y. F.; Luo, Q. Q.; Zhang, W. H.; Li,D. Q.; Yang, J. L.; Xie,Y. Partially Oxidized Atomic Cobalt Layers for Carbon Dioxide Electroreduction to Liquid Fuel. Nature 2016, 529, 68-71. (13) Zhu, W. L.; Zhang,Y. J. ; Zhang, H. Y. ; Lv, H. F.; Li, Q. ; Michalsky,R.; Peterson, A. A.; Sun,S. H. Active and Selective Conversion of CO2 to CO on Ultrathin Au Nanowires. J. Am. Chem. Soc. 2014, 136, 16132-16135. (14) Hansen, H. A.; Varley, J. B.; Peterson, A. A.; Norskov, J . K. Understanding Trends in the Electrocatalytic Activity of Metals and Enzymes for CO2 Reduction to CO. J. Phys. Chem. Lett. 2013, 4, 388-392.



Page 18 of 21

(15) Nie, X.; Esopi, M. R.; Janik, M. J.; Asthagiri, A. Selectivity of CO2 Reduction on Copper Electrodes: The Role of the Kinetics of Elementary Steps. Angew. Chem. Int. Ed. 2013, 52, 2459-2462. (16) Taguchi, S.; Aramata, A.; Enyo, M. Reduced CO2 on Polycrystalline Pd and Pt Electrodes in Neutral Solution: Electrochemical and In Situ Fourier Transform IR Studies. J. Electroanal. Chem. 1994, 372, 161-169. (17)

Tian, N.; Zhou, Z.-Y.; Sun, S.-G.; Ding, Y.; Wang , Z. L. Synthesis of

Tetrahexahedral Platinum Nanocrystals with High-index Facets and High Electrooxidation Activity. Science 2007, 316, 732-735. (18)

Jiang, B.; Li, C. L.; Malgras, V.; Imura, M.; Tominakaa, S.; Yamauchi, Y.

Mesoporous

Pt

Nanospheres

with

Designed

Pore

Surface

as

Highly

Active

Electrocatalyst. Chem. Sci. 2016, 7, 1575-1581. (19) Li, C. L.; Sato, T.; Yamauchi, Y. Electrochemical Synthesis of One-dimensional Mesoporous Pt Nanorods Using the Assembly of Surfactant Micelles in Confined Space. Angew. Chem. Int. Ed. 2013, 52, 8050-8053. (20) Wang, H. J.; Jeong H. Y.; Imura, M.; Wang, L.; Radhakrishnan, L.; Fujita, N.; Castle, T.; Terasaki, O.; Yamauchi, Y. Shape- and Size-controlled Synthesis in Hard Templates: Sophisticated

Chemical

Reduction

for

Mesoporous

Nanoparticles. J. Am. Chem. Soc. 2012, 133, 14526-14529.


Monocrystalline

Platinum

Page 19 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

(21) Hoshi, N.; Mizumura, T.; Hori, Y. Significant Difference of the Reduction Rates of Carbon Dioxide between Pt (111) and Pt (110) Single Crystal Electrodes. Electrochimica Acta 1995, 40, 883-887. (22) Lee, S. W.; Chen,S.; Sheng,W.; Yabuuchi, N.; Kim,Y.-T.; Mitani, T. ; Vescovo, E.; Shao-Horn,Y. Roles of Surface Steps on Pt Nanoparticles in Electro-oxidation of Carbon Monoxide and Methanol. J. Am. Chem. Soc. 2009, 131, 15669-15677. (23) Kortlever, R.; Peters, I.; Koper,S. ; Koper, M. T. M. Electrochemical CO2 Reduction to Formic Acid at Low Overpotential and with High Faradaic Efficiency on CarbonSupported Bimetallic Pd-Pt Nanoparticles. Acs Catal. 2015, 5, 3916-3923. (24) Centi, G.; Perathoner, S.; Wine, G.; Gangeri, M. Electrocatalytic Conversion of CO2 to Long Carbon-chain Hydrocarbons. Green Chem. 2007, 9, 671-678. (25) Gangeri, M.; Perathoner,S.; Caudo, S.; Centi,G.; Amadou, J.; Begin, D.; PhamHuu,C.; Ledoux, M. J.; Tessonnier,J. P.; Su, D. S. ; Schloegi, R. Fe and Pt Carbon Nanotubes for the Electrocatalytic Conversion of Carbon Dioxide to Oxygenates. Catal. Today 2009, 143, 57-63. (26) Kuhl, K. P.; Cave, E. R.; Abram, D. N.; Jaramillo, T. F. New Insights into the Electrochemical Reduction of Carbon Dioxide on Metallic Copper Surfaces. Energy Environ. Sci. 2012, 5, 7050-7059. (27) Kuhl, K. P.; Hatsukade, T.; Cave, E. R.; Abram, D. N.; Kibsgaard, J.; Jaramillo, T. F. Electrocatalytic Conversion of Carbon Dioxide to Methane and Methanol on Transition Metal Surfaces. J. Am. Chem. Soc. 2014, 136, 14107-14113.



(28)

Brisard, G. M., Camargo, A. P. M., Nart, F. C.,

Page 20 of 21

Iwasita, T. On-line Mass

Spectrometry Investigation of the Reduction of Carbon Dioxide in Acidic Media on Polycrystalline Pt. Electrochem. Commun. 2001, 3, 603-607. (29) Hori, Y.; Koga, O.; Yamazaki, H.; Matsuo, T. Infrared Spectroscopy of Adsorbed CO and Intermediate Species in Electrochemical Reduction of CO2 to Hydrocarbons on a Cu Electrode. Electrochim. Acta 1995, 40, 2617-2622. (30) Hoshi, N.; Suzuki, T.; Hori, Y. Catalytic Activity of CO2 Reduction on Pt SingleCrystal Electrodes: Pt(S)-[n(111)×(111)], Pt(S)-[n(111)×(100)], and Pt(S)-[n(100)×(111)]. J. Phys. Chem. B 1997, 101, 8520-8524. (31) Gumhalter, B.; Hermann, K.; Wandelt, K. Perturbation of the Adsorbate Electronicstructure by Local Field at Surface. Surf. Sci. 1991, 251, 1128-1132. (32) Hoshi, N.; Suzuki, T.; Hori,Y. Step Density Dependence of CO2 Reduction Rate on Pt (S)-[n (111)×(111)] Single Crystal Electrodes. Electrochim. Acta 1996, 41, 1647-1653. (33) Taguchi, S.; Ohmori,T.; Aramata, A.; Enyo, M. Adsorption of CO and CO2 on Polycrystalline Pt at a Potential in the Hydrogen Adsorption Region in Phosphate Buffer Solution: An In Situ Fourier Transform IR study. J. Electroanal. Chem. 1994, 369, 199205. (34)

Kumar, B., Atla, V., Brian, J. P., Kumari, S., Nguyen, T. Q., Sunkara, M.,

Spurgeon, J. M. Reduced SnO2 Porous Nanowires with a High Density of Grain Boundaries as Catalysts for Efficient Electrochemical CO2-into-HCOOH Conversion. Angew. Chem. Int. Ed. 2017, 56, 3645-3649.


Page 21 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Energy Letters

(35)

Roman, T. ; Nakanishi, H.; Kasai, H. Coadsorbed H and CO Interaction on

Platinum. Phys. Chem. Chem. Phys. 2008, 10, 6052-6057. (36)

Creighan, S. C.; Mukerji, R. J.; Bolina, A. S.; Lewis, D. W.; Brown. W. A. The

Adsorption of CO on the Stepped Pt{211} Surface: A Comparison of Theory and Experiment. Catal. Lett. 2003, 88, 39-45. (37) Carrasco, E.; Aumer, A.; Brown, M. A.; Dowler. R. Infrared Spectra of High Coverage CO Adsorption Structures on Pt(111). Surf. Sci. 2010, 604, 1320-1325. (38) Hammer, B.; Nielsen, O. H.; Norskov, J. K. Structure Sensitivity in Adsorption: CO Interaction with Stepped and Reconstructed Pt Surfaces. Catal. Lett. 1997, 46, 31-35. (39) Back, S.; Kim, H; Jung, Y. Selective Heterogeneous CO2 Electroreduction to Methanol. ACS Catal. 2015, 5, 965-971. (40) Montoya, J. H.; Peterson, A. A.; Norskov, J. K. Insights into C-C Coupling in CO2 Electroreduction on Copper Electrodes. Chemcatchem 2013, 5, 737-742.


Hierarchically Ordered Nanochannel Array Membrane Reactor with

Recommend Documents