Non-Noble Metal Nanoparticles Supported by Postmodified Porous

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Non-Noble Metal Nanoparticles Supported by Post-Modified Porous Organic Semiconductors: Highly Efficient Catalysts for VisibleLight-Driven On-Demand H Evolution from Ammonia Borane 2

Hao Zhang, Xiaojun Gu, Jin Song, Na Fan, and Haiquan Su ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.7b10280 • Publication Date (Web): 07 Sep 2017 Downloaded from http://pubs.acs.org on September 10, 2017

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ACS Applied Materials & Interfaces

Non-Noble Metal Nanoparticles Supported by PostModified Porous Organic Semiconductors: Highly Efficient Catalysts for Visible-Light-Driven OnDemand H2 Evolution from Ammonia Borane Hao Zhang, Xiaojun Gu,* Jin Song, Na Fan, and Haiquan Su* Inner Mongolia Key Laboratory of Coal Chemistry, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, Inner Mongolia, China. KEYWORDS: hydrogen evolution, metal nanoparticle, semiconductor, catalyst, visible light irradiation

ABSTRACT: From the viewpoint of controlling the visible-light-driven activities of catalysts containing metal nanoparticles (NPs) by tuning the microstructures of semiconducting supports, we employed a post-synthetic thermal modification approach to prepare carbon nitride (C3N4) species featuring different microstructures and then we synthesized Co and Ni NPs supported by these C3N4 species, which were used to catalyze the room-temperature H2 evolution from ammonia borane (NH3BH3). The systematic investigation showed that the catalysts had different activities under light irradiation. Compared with the pristine C3N4-based catalyst, all the modified C3N4-based catalysts had enhanced activities. The highest active Co catalyst with total

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turnover frequency (TOF) of 93.8 min−1 was successfully obtained, which exceeded the values of all the reported heterogeneous noble metal-free catalysts. The structure characterizations indicated that the post-modified porous C3N4 species had the different band structures, photoluminescence lifetime and photocurrent density under visible light irradiation, leading to the different separation efficiency of photogenerated charge carriers. These characteristics helped us regulate the electronic characteristics of Co and Ni NPs in the supported catalysts and then led to the significantly different and enhanced activity in the visible-light-driven H2 evolution.

1. INTRODUCTION Currently, hydrogen (H2) has been used as a clean fuel to potentially solve the energy crises.1,2 Because of the low boiling point, H2 is difficult to be stored in compressed or liquefied forms, which becomes one of the major challenges in establishing the hydrogen economy related to fuel cells.3-6 As a consequence, the chemical hydrogen storage in metal hydrides and molecular hydrides has been widely explored.7-9 Ammonia borane (NH3BH3), which has the ultrahigh hydrogen content (19.6 wt%, 146 g⋅L−1) and the property of mildly generating H2, is a promising candidate for chemical hydrogen storage.10-14 Although the dehydrogenation of NH3BH3 (NH3BH3+2H2O→NH4BO2+3H2) can proceed by means of heterogeneous catalysts including metal nanoparticles (NPs), the faster release of H2 is desirable but remains a challenge using nonnoble metal catalysts.15-25 Among the various methods, regulating the electron density of active species is effective in enhancing their catalytic activities.26-29 In the supported catalysts, using the alloying effect of different types of metals and the interaction between metal and support is popular to realize this aim.30-33 Indeed, the utilization of both methods has been successful in enhancing the activities of catalysts in the various reduction-dominated catalytic reactions


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including H2 evolution from NH3BH3;34-36 however, the activities of non-noble metals have not been yet remarkably enhanced,37-47 probably due to that the increased extent of their electron density is not as high as we expect. In view of this situation, developing new methods to regulate the electron density of non-noble metal catalysts is urgent and necessary for the practical application of NH3BH3, especially in the portable and on-demand fields requiring H2. Solar light containing photons can be used as driving force to accelerate proton reductions such as water splitting through regulating the electron structures of catalytically active metal centers.48-50 However, the noble metal-based catalysts still remain to exhibit more significantly enhanced activities than the catalysts only consisting of non-noble metals in the photocatalytic H2 evolution reactions since these non-noble metals have low work functions. So, how to further improve the activities of non-precious catalysts under visible light irradiation and discover the relationship between their catalytic behaviors and microstructures become necessary and urgent. Among the various factors, the charge separation of semiconducting support in a Mott-Schottky catalyst containing metal NPs might be the key factor influencing the catalytic activity.51-53 To this end, tuning the microstructures of semiconducting supports could be an efficient method to improve the charge separation efficiency and then to improve the photogenerated electron density of their conduction bands. More importantly, in the Mott-Schottky catalysts, the nonnoble metal NPs could trap and collect more photogenerated electrons from semiconducting supports and then accelerate the reduction of hydride complexes including NH3BH3. Herein, we designed and synthesized a series of porous semiconducting graphitic carbon nitrides (C3N4) with modified and tunable microstructures, and then developed a suite of supported Co and Ni NPs, which were used as catalysts for H2 evolution from NH3BH3 under visible light irradiation. Remarkably, in comparison with the pristine C3N4-based Co catalyst


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with total turnover frequency (TOF) of 44.1 min−1, one modified C3N4-based Co catalyst had the expressively increased photocatalytic activity with the highest TOF of 93.8 min−1 at 298 K. Moreover, we also studied the relationship between the catalytic performance and the microstructures of catalysts and investigated the role of light’s intensity and wavelength in the catalytic process. 2. EXPERIMENTAL SECTION 2.1 Chemicals. All the chemicals were commercial. Dicyandiamide (C2H4N4, Aldrich, 99%), cobalt chloride hexahydrate (CoCl2·6H2O, Sinopharm Chemical Reagent Co., Ltd, >99%), nickel chloride hexahydrate (NiCl2·6H2O, Tianjin Fengchuan Chemical Reagent Technologies Co., Ltd, >99%), ammonia borane (NH3BH3, Aldrich, 97%), sodium borohydride (NaBH4, J&K Chemical, 99%) and deionized water were used in all the experiments. 2.2 Synthesis and Catalytic Study. The pristine C3N4 was synthesized by heating dicyandiamide in Ar atmosphere at 500 oC for 4 h.54,55 To prepare the C3N4 species with modified microstructures, the pristine C3N4 powder was heated at a series of designed temperatures (540, 560, 580, 600, 620 and 630 oC) for 2 h. The C3N4 species obtained by the post-synthetic thermal modification approach were labelled as C3N4-540, C3N4-560, C3N4-580, C3N4-600, C3N4-620 and C3N4-630. Co or Ni NPs supported by pristine and modified C3N4 species were labelled as Co/C3N4, Co/C3N4-540, Co/C3N4-560, Co/C3N4-580, Co/C3N4-600, Co/C3N4-620, Co/C3N4-630, Ni/C3N4, Ni/C3N4-540, Ni/C3N4-560, Ni/C3N4-580, Ni/C3N4-600, Ni/C3N4-620 and Ni/C3N4-630. The process of preparing the above catalysts and their catalytic study was following: the aqueous solution (1.0 mL) of C3N4 (18 mg) and CoCl2·6H2O/NiCl2·6H2O (0.034 mmol) was stirred in a two-necked flask for 5 h. The catalytic reaction began right way at 298 K when the aqueous


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solution (1.5 mL) of NH3BH3 (1.71 mmol) and NaBH4 (0.068 mmol) was added into the above mixture. During the catalytic reaction, the process of gas generation was monitored. To test the stability of catalysts, 1.71 mmol of NH3BH3 was syringed into the reaction after the previous H2 evolution finished. The total catalytic cycles were 25 times under visible light irradiation. During the two adjacent cycles, the interval was 5 min. 2.3 Catalyst Characterization. The spectrometer (Thermo Fisher Scientific, NEXUS-670) and the automatic absorption apparatus (Autosorb-iQ2-MP) were used to measure the infrared (IR) spectra and the N2 adsorption/desorption of samples, respectively. The X-ray diffractometer (Panalytical, X-Pert PRO) and the instrument (Thermo VG Corp., ESCALAB250) were selected to measure the powder X-ray diffraction (PXRD) and X-ray photoelectron spectra (XPS) of samples, respectively. The morphologies and compositions of supports and catalysts were measured using a transmission electron microscopy (TEM, JEM-2010) containing the energy dispersive X-ray (EDX) detector. Shimadzu UV-3600 and FLS920 spectrometers were used to measure the UV-vis and photoluminescence (PL) spectra of samples, respectively. The Vario EL CHNOS analyser was used to measure the contents of C, H and N in the supports. The LabRAM HR Evolution spectrometer was used to measure the Raman spectra of samples. Under light irradiation (> 420 nm), the transient photocurrent measurement was performed in an electrochemical instrument (PGSTAT302N, Switzerland). An indium tin oxide (ITO) glass plate coated with C3N4 species, an Ag/AgCl electrode and a Pt plate were used as the working electrode, the reference electrode and the counter electrode, respectively.


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3. RESULTS AND DISCUSSION

Figure 1. Illustration of the visible-light-driven catalytic procedure over non-noble metal catalysts based on the post-modified C3N4 species with different microstructures. 3.1. Synthesis. C3N4 was selected as semiconducting support since it is a metal-free, twodimensional organic semiconductor and its structure can be modified through various methods such as copolymerization, doping, nanostructuring and post-synthetic thermal modification.56-60 It has a suitable bandgap (≈ 2.7 eV) and the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) are located at about +1.6 and −1.1 eV, respectively, which is qualified for the redox reaction. Considering the structure tailorability and the high stability of C3N4 up to 650 oC, the post-synthetic thermal modification can be conducted by heating the pristine C3N4 at different temperatures from 540 to 630 oC,61,62 leading to porous C3N4 products with different components and electron structures. Thus, with the help of the built-in electric field, the photogenerated electrons could be efficiently transferred from modified C3N4 to non-noble metal NPs and the resultant electron density of metal NPs could be tuned and enhanced (Figure S1). In addition, the post-synthetic thermal modification of organic C3N4 can generate the pores on its surface,63-65 which provides more catalytic active sites and adsorption sites to accelerate H2 evolution from NH3BH3. From the above-mentioned contents, the catalytic


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H2 evolution activities of the non-noble metal NPs supported by porous C3N4 species with different microstructures, which were synthesized using the simple post-synthetic thermal modification approach, would be rationally tuned and dramatically improved under visible light irradiation (Figure 1). 3.2 Characterization of Modified C3N4 Species. The PXRD patterns of the pristine and modified C3N4 species showed that every C3N4 had a dominant peak at about 27.2o and another peak at about 13.1o, which were ascribed to the (002) plane of layer structure and the (100) plane of heptazine, respectively (Figure S2). Moreover, after the thermal treatment, the C3N4 species became thinner.66-68 Based on the Scherrer formula, the calculated layer numbers of pristine C3N4, C3N4-540, C3N4-560, C3N4-580, C3N4-600, C3N4-620 and C3N4-630 were 15, 13, 12, 11, 10, 9 and 7, respectively. The IR spectra of the modified C3N4 species showed the stretching modes of carbon nitride heterocycles (1230−1660 cm−1) and the bending mode of triazine heterocycles (810 cm−1) (Figure S3). The Raman spectra showed that the pristine and modified C3N4 species exhibited the typical Raman resonances of C3N4 (Figure S4).69 From Figure S5, it could be found that every XPS survey spectrum contained two domain peaks at about 398.7 and 288.2 eV and they were ascribed to the signals of N 1s and C 1s, respectively.56-65 In detail, the dominant C 1s peaks with binding energies in the ranges of 288.1−288.3 eV corresponded to the C(N)3 and N 1s peaks around 398.7 eV attributed to N(C)3 groups in C3N4, respectively (Figure S6). Compared to the pristine C3N4, the post-modified C3N4 species had higher binding energies of N 1s and C 1s, but they had small variations (Table S1). This might be resulted from the charge redistribution of carbon nitrides featuring the different C/N ratios and microstructures.64 All the above results suggested the basic frameworks of C3N4 species were retained after the thermal treatment,56-65 which ensured their semiconducting characteristics and the resultant


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photocatalytic performance. In addition, compared with the typical stacked and slate morphology of pristine C3N4, many pores formed in the modified C3N4 species (Figure S7), which was beneficial for the catalysis owing to the existence of more catalytic active centers. The surface areas increased from 7.2 m2⋅g−1 of the pristine C3N4 to 19.0, 23.9 and 28.5 m2⋅g−1 of the modified C3N4 species obtained at 540, 580 and 620 oC, respectively, indicating the presence of abundant pores (Figures S8-S11). The average pore sizes of C3N4, C3N4-540, C3N4-580 and C3N4-620 were 6.6, 6.1, 5.2 and 5.0 nm, respectively. The formation of porous structures could be ascribed to the breaking of hydrogen bonds between the melon strands in the modified C3N4 species.64,65. Moreover, with increasing the temperature, the hydrogen bonds became easier to be broken, which led to the increasing surface areas of C3N4 species.

Figure 2. UV-vis diffuse reflectance spectra of the pristine and modified C3N4 species. Compared with the pristine C3N4, the modified C3N4 species had notable red shifts of the absorption edges in the UV-vis spectra (Figure 2), which promoted the harvest of more visible light. In view of the excitation of band tails/localized states, a broadened absorption band, which started from 450 nm of onset to 636 nm of end, appeared in the spectrum of the pristine C3N4 (Figure S12). The spectra also indicated that the range of absorbance from the band tails and the


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intrinsic bands expanded in the modified C3N4 species. When the treatment temperature increased, the absorbance from band tails exhibited a gradual increase. These changes were caused by the changed microscopic and electronic structures of C3N4 species by heating at different temperatures, as demonstrated by the elemental analysis (Table S2) and the band tails/localized states with different distribution. The thermal treatment also led to the suppressive recombination of electrons and holes in C3N4 species. This was also confirmed by the weaken PL peaks (Figure 3a). To understand the lifetime of photogenerated charge carriers, we monitored the time-resolved PL spectra of all the C3N4 species. From the spectra (Figure 3b), it could be found the shortening of PL lifetime of modified C3N4 species with increasing the treatment temperatures. In addition, the modification of microstructures of C3N4 species under thermal treatment caused the increased density of band tails, which enhanced the occurring probability of such rapid PL processes. The photoelectrochemical investigation displayed that the photocurrent of modified C3N4 species increased when the temperature was raised to 580 oC (Figure 4). This confirmed the enhanced charge separation efficiency after the thermal modification, leading to the increased lifetime of electrons/holes. It should be noted that the photocurrent of modified C3N4 obtained at 620 oC decreased. This phenomenon illustrated that the charge carriers were trapped by the band tails/localized states with high density and then their transition was significantly inhibited.64,65 All the above optical and photoelectrochemical results indicated that the modified C3N4 species with different microstructures could be used as efficient semiconducting supports to tune and accelerate the electron transfer from supports to metal NPs, resulting in the remarkably high catalytic activities under visible light irradiation.


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Figure 3. (a) PL spectra and (b) time-resolved PL spectra of the pristine and modified C3N4 species.

Figure 4. Profiles of time versus transient photocurrent density of the pristine and modified C3N4 species.


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Figure 5. TEM images and the SAED patterns (insets) of (a) Co/C3N4-580 and (b) Ni/C3N4-580 and the elemental maps of Co/C3N4-580 for (c) Co, (d) C and (e) N and Ni/C3N4-580 for (f) Ni, (g) C and (h) N. 3.3 Characterization of Catalysts. The PXRD patterns showed that there were the distinctive diffractions of C3N4 species and no diffractions of Co components in the Co-based catalysts (Figure S13), suggesting that the Co NPs were amorphous, which was caused by the in situ reduction of Co2+ during the synthesis of catalysts.47 The investigation of XPS patterns exhibited that the peaks of 856.0−856.9, 873.0−873.9, 781.0−781.9 and 796.9−797.9 eV were ascribed to the binding energies of Ni 2p3/2 and Ni 2p1/2 of NiO and Co 2p3/2 and Co 2p1/2 of CoO, respectively. The presence of metal oxides in the catalysts illustrated that the metal NPs were oxidized in the air (Figures S14-S18). However, after Ar etching, the peaks of 778.1−778.9, 793.0−793.9 852.1−852.9 and 870.0−870.9 eV were found, implying that Co and Ni in the metallic state were the catalytically active species. From the TEM results, it was found that the


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metal NPs in Co/C3N4, Co/C3N4-540, Co/C3N4-580, Co/C3N4-620 and Ni/C3N4-580 had few aggregates and different sizes and shapes (Figure 5 and Figures S19-S21), which was caused by the different interface interactions between Co NPs and C3N4 supports with different compositions, porous structures and electronic characteristics after the thermal treatment. The SAED patterns showed that the amorphous metal NPs existed in the five catalysts. In the elemental maps obtained from the high angle annular dark field scanning TEM (HAADF-STEM), there was no apparent contrast change, confirming that the metal species dispersed on the supports. The existence of Co and Ni components in the supported catalysts was testified by the EDX results (Figures S22-S26). The absorption bands of C3N4 supports and the corresponding catalysts were similar in the UV-vis spectra (Figure 2 and Figure S27), but the absorption intensity of catalysts was enhanced, which ensured more photogenerated electrons formed. 3.4 Catalytic Performance. To explore how the light irradiation affected the H2 evolution from NH3BH3, the catalytic activities of the seven catalysts Co/C3N4, Co/C3N4-540, Co/C3N4560, Co/C3N4-580, Co/C3N4-600, Co/C3N4-620 and Co/C3N4-630 were checked. The results showed that the photocatalytic activities of the catalysts were higher than those in in the dark and the modified C3N4-supported Co catalysts displayed enhanced photocatalytic H2 evolution activities than the pristine C3N4-supported Co catalyst (Figure 6). Also, the activities of catalysts in the dark decreased with increasing the treatment temperatures during the synthesis of modified C3N4 supports and their photocatalytic activities exhibited the different orders. Specifically, the photocatalytic H2 evolution activities of the catalysts increased when the temperature increased up to 580 oC. The activities decreased when the temperature further increased, but they remained to be higher than the activity of the pristine C3N4-based Co catalyst. The activity decreased beyond 580 oC probably due to that the band tails/localized states with high density formed in


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C3N4 support after thermal treatment above 580 oC, which restrained the electron transfer in the catalytic process.64,65 It was surprising that Co/C3N4-580 had the photocatalytic H2 evolution activity with the TOF of 93.8 min−1. This value exceeded the values of all the reported non-noble catalysts, i.e. Co/CTF (42.3 min−1),46 Co NPs (39.8 min−1),37 Co/PEI-GO (39.9 min−1)39 and Cu0.8Co0.2O-GO (70 min−1),45 and was comparable to the values of some catalysts only consisting of noble metals, i.e. AgPd/UiO-66-NH2 (90 min−1),13 Rh@PAB (130 min−1)11 and Ru/HAP (137 min−1).12 Moreover, the activity enhancement of 54.6, 94.2, 105.6, 131.6, 99.7, 104.9 and 110.4 % of Co/C3N4, Co/C3N4-540, Co/C3N4-560, Co/C3N4-580, Co/C3N4-600, Co/C3N4-620 and Co/C3N4-630 was ascribed to the contribution of light irradiation compared with the dark reaction, respectively.

Figure 6. (a) Time versus volume of evolved H2 from NH3BH3 over a series of catalysts under different conditions and (b) the total TOF values. To check the generality of the present catalytic strategy, the catalytic performance of the seven Ni-based catalysts (Ni/C3N4, Ni/C3N4-540, Ni/C3N4-560, Ni/C3N4-580, Ni/C3N4-600, Ni/C3N4620 and Ni/C3N4-630) was also studied. The results showed that their photocatalytic activities were also improved in comparison with their activities in the dark and the orderliness of catalytic activities was similar to that in Co-based catalysts (Figure S28). It should be noted the Ni-based


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catalysts had the lower activities than the Co-based catalysts. Moreover, the visible light irradiation led to the activity enhancement of 85.7, 138.6, 143.0, 171.2, 143.8, 133.3 and 115.7 % of Ni/C3N4, Ni/C3N4-540, Ni/C3N4-560, Ni/C3N4-580, Ni/C3N4-600, Ni/C3N4-620 and Ni/C3N4630, respectively.

Figure 7. (a) Time versus volume of evolved H2 from NH3BH3 over Co/C3N4-580 under the light irradiation with different wavelengths and (b) the dependence of total TOF values (left axis) and the activity enhancement (right axis) on incident light’s wavelength. In order to deeply understand the role of light in the reaction, we investigated the influence of the intensity and wavelength of visible light on the H2 evolution using Co/C3N4-540, Co/C3N4580 and Ni/C3N4-580. For the study of wavelength, the three catalysts Co/C3N4-540, Co/C3N4580 and Ni/C3N4-580 gave the activities with TOF values of 83.3, 93.8 and 22.4 min−1, respectively, under light irradiation with wavelength range of 420-800 nm (Figure 7 and Figures S29 and S30). The TOF values of the three catalysts, which were irradiated in the wavelength ranges of 490-800, 550-800 and 600-800 nm, decreased in sequence. For Co/C3N4-580, the TOF values decreased to 71.4, 57.7 and 51.7 min−1 with the above wavelength ranges. Since the TOF value of Co/C3N4-580 in the dark was 40.5 min−1, the irradiation in the wavelength ranges of 600-800, 550-800, 490-800 and 420-800 nm accounted for the activity enhancement of about


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1.3-, 1.4-, 1.8- and 2.3-fold, respectively. The similar results were also observed for Co/C3N4540 and Ni/C3N4-580. As a result, in the wavelength range of 420-550 nm, the catalysts had the highest activities. When the wavelength range of 420-800 nm was fixed, the influence of light intensity on the catalytic reaction was studied. The results showed that the higher light intensity had the greater contribution on the enhancement of catalytic activities and the H2 evolution rate had the almost linear increase (Figure 8 and Figures S31 and S32). Especially for Co/C3N4-580, about 24, 43 and 57% of activity contribution came from the incident light with 100, 300 and 500 mW/cm2, respectively. The above phenomena could be ascribed to that more photogenerated electrons were motivated under the light irradiation with high intensity and low wavelength, leading to the enhanced activities of visible-light-responsive non-noble metal nanocatalysts.

Figure 8. (a) Time versus volume of evolved H2 from NH3BH3 over Co/C3N4-580 under the light irradiation with different intensities and (b) the dependence of total TOF values on incident light’s intensity. The photocatalytic long-time durability tests of Co/C3N4-540, Co/C3N4-580 and Ni/C3N4-580 were performed at 298 K. The results showed that the H2 selectivity did not change and their activities decreased after 25 runs (Figure 9 and Figure S33). The TOF values of Co/C3N4-540, Co/C3N4-580 and Ni/C3N4-580 after the long-time catalytic tests were 8.6, 8.9 and 5.1 min-1,


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respectively. The relatively high stability of catalysts could be caused by the immobilization of metal NPs using nitrogen-enriched C3N4 and the decrease of their catalytic activities was probably caused by the partial agglomeration of metal NPs (Figure S34). Of course, the catalytically active sites could be easily blocked by boron species, always resulting in the activity decrease during the catalytic process.37-47

Figure 9. Long-time photocatalytic durability test for evolved H2 from NH3BH3 over the catalysts. 4. CONCLUSION In summary, we fabricated non-precious Co and Ni NPs supported by a series of post-modified C3N4 species. They had dramatically different and intensive room-temperature activities in the dehydrogenation of NH3BH3 under light irradiation. To our delight, the activity, which was superior to the activities of all the reported noble metal-free catalysts, was successfully obtained. The thermally treated C3N4 species with the enlarged surface areas, the extended light absorption and the enhanced separation efficiency of electrons/holes ensured the highly efficient electron transfer process under light irradiation, resulting in the improved electron density of Co and Ni NPs and the resultant enhanced photocatalytic H2 evolution activities. In addition, the activity


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increased with the dependence of light’s intensity and wavelength testified that the enhancement of the electron density of Co and Ni NPs in the supported catalysts containing semiconductors was caused by the visible light irradiation. These results provide a cost-effective approach to tailor the electron behaviors of metal NPs through tuning the microstructures of semiconducting supports, which benefits the improved catalytic performance in photocatalysis, electrocatalysis and thermocatalysis. ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at http://pubs.acs.org. PXRD, TEM images, EDX, Raman spectra, XPS, UV-vis spectra, N2 adsorption/desorption isotherms, elemental analysis and the experimental results for H2 evolution from ammonia borane. AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected]. *E-mail: [email protected]. ORCID Xiaojun Gu: 0000-0002-3877-4373 Haiquan Su: 0000-0003-2164-3219 Notes


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The authors declare no competing financial interest. ACKNOWLEDGMENTS This work was supported by the Program for New Century Excellent Talents in University of the Ministry of Education of China (grant no. NCET-13-0846), the Program for Young Talents of Science and Technology in Universities of Inner Mongolia Autonomous Region (grant no. NJYT-13-A01) and the Prairie Excellence Innovation and Entrepreneurial Team of Inner Mongolia (201201).

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Table of Contents Graphic


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Non-Noble Metal Nanoparticles Supported by Postmodified Porous

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