IrCo nanodendrite as an efficient bifunctional electrocatalyst for overall

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IrCo nanodendrite as an efficient bifunctional electrocatalyst for overall water splitting under acidic condition Luhong Fu, Xiang Zeng, Gongzhen Cheng, and Wei Luo ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.8b08717 • Publication Date (Web): 17 Jul 2018 Downloaded from http://pubs.acs.org on July 18, 2018

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ACS Applied Materials & Interfaces

IrCo nanodendrite as an efficient bifunctional electrocatalyst for overall water splitting under acidic condition Luhong Fu, Xiang Zeng, Gongzhen Cheng and Wei Luo* College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, Hubei 430072, P. R. China, Tel.: +86-27-68752366 *Corresponding author. E-mail addresses: [email protected]

KEYWORDS: Water splitting, nanodendrites, IrCo, hydrogen evolution reaction, oxygen evolution reaction

ABSTRACT

Investigation of high-efficiency electrocatalysts for acidic overall water splitting is of great significance toward fulfillment of proton exchange membrane (PEM) electrolyzers, but still remains challenging. Herein, we report the colloidally synthesis of IrCo alloy nanodendrites with

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petal-like architecture (NDs). Benefiting from unique hierarchical architecture and strong electronic interaction arising from synergistic alloying effect of IrCo at the atomic level, the resultant IrCo0.65 NDs display remarkable hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances with overpotentials of 17 and 281 mV to achieve 10 mA cm-2 in 0.1 M HClO4, respectively. Moreover, when further used as bifunctional electrocatalyst toward acidic overall splitting, a low cell voltage of 1.593 V is achieved at 10 mA cm-2.

Electrocatalytic water splitting is a well-established commercial method to generate hydrogen with high purity, which involves anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER).1-9 Continuous performances have been conducted toward water splitting in alkaline condition in the last few decades,4-7 while the exploration for acidic water splitting is much more challenging due to the slow conversion efficiency caused by the extremely sluggish reaction kinetics of OER at the anode, as well as unstability of electrocatalysts in highly corrosive acidic environment during OER process,10 which severely hinder the wide utilization of proton exchange membrane (PEM) electrolyzers. Moreover, it has been reported that the experimental reaction rate of HER in basic solution is much slower than that in acidic solution.11 So, developing highly efficient catalysts toward acidic water splitting is worthwhile but still endures predicament. Currently, iridium oxides (IrOx) have been considered as supremely efficient catalysts toward OER in acidic media.12-14 Moreover, several recent reports have pointed out that Ir-based catalysts also exhibit superior catalytic activity toward HER.15 Nevertheless, the relative high cost greatly limit its large-scale application. Introduce non-noble metals, i.e., Fe, Co, Ni and Cu,


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into Ir to form Ir-based alloys or other hybrids, which could not only decrease the consumption of Ir but also improve the catalytic performance due to the synergistic electronic effect.15-17 Furthermore, the morphologies of nanocatalysts usually have significant influence on their catalytic performances.18-23 A series of Ir-based nanocrystallites with different structures, such as ultrathin laminar superstructure,18 hollow nanocrystals,19,

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nanowires,21 nanoneedles22 and

nanotubes,23 have been developed for efficient electrocatalytic applications. For instance, Lee reported ultrathin IrO2 nanoneedles for superior OER performance in acidic solution.22 Huang reported ultrathin laminar Ir superstructures for efficient acidic OER.18 Guo’s group reported multimetallic porous hollow nanocrystals (PHNCs) (IrCoNi PHNCs) toward acidic overall water splitting.19 In addition, our group reported ultrathin Ir wavy nanowires24 and monodisperse IrNiFe nanoparticles (NPs)25 with low cell voltages for acidic water splitting, respectively. Despite substantial efforts have been executed for designing Ir-based materials with fascinated architectures, their electrocatalytic performances toward OER, especially as bifunctional electrocatalysts for acidic water splitting are still unsatisfactory. Inspired by the previous works, herein, we reported a colloidal synthesis of homodispersed IrCo alloy nanodendrites with petal-like architecture (NDs). It has been reported that the anisotropy of nanodendrites is particularly favorable to the electrocatalytic kinetics and stabilities.26 Thanks to the unique morphology and strong synergistic interaction among Ir, Co at the atomic lever, the resulted IrCo NDs exhibit superior HER and OER performances, with overpotentials of 17 and 281 mV to drive 10 mA cm-2, comparable to those of Pt/C and IrO2. When further used as bifunctional electrocatalyst for overall water splitting in acidic media, a low cell voltage of 1.593 V would be achieved at10 mA cm-2.


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IrCo alloy nanodendrites (NDs) were prepared through a simple colloidally synthetic method under the protection of nitrogen (N2) flow in oleylamine (OAm), which used as both surfactant agent and reductant. Iridium chloride hydrate (IrCl3·xH2O) and cobalt acetylacetonate [Co(acac)2] were selected as the precursors of Ir source and Co source, respectively. We defined the IrCo alloy NDs as IrCo0.65 based on inductively coupled plasma-atomic emission spectroscopy (ICPAES) result. Corresponding characterizations for features of IrCo0.65 are illustrated in Figure 1. Figure 1a, b, and c show the morphology characterized via transmission electron microscopy (TEM), which display the feature of homodispersed nanodendrites with a solid core surrounded by petal-like structures. The average grain size is measured to be about 19 nm. This anisotropic architecture with enhanced surface area and active sites may also facilitate the evolved gas release during catalysis, resulting in its superior electrocatalytic performance (vide infra).26 As shown in Figure 1d, Energy-dispersive X-ray spectroscopy (EDX) spectrum indicates that Ir and Co were both existent, with an atomic ratio of 62.9% to 37.1%, which is coincide with ICP result. Powder X-ray diffraction (XRD) pattern (Figure 1d) shows three obvious peaks with a higher peak at 41.8°, a lower peaks at 71.2°, and a shoulder peak at 48.3°. The locations of these tree peaks are between the (111), (220), and (200) planes of face-centered cubic (fcc) Ir (PDF# 060598) and fcc Co (PDF# 15-0806), suggesting the formation of IrCo alloy.17 High-resolution TEM (HRTEM) shows the lattice plane spacings are 0.214 and 0.187 nm, between Ir (111) and Co (111) planes, Ir (200) and Co (200) planes, respectively, further proving the formation of IrCo alloy (Figure 1c).


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Figure 1. (a, b) TEM images and (c) HRTEM image for as-prepared IrCo0.65 nanodendrites. Insert in (b) is the corresponding size statistics. (d) EDX spectrum of IrCo0.65 NDs. (e) The corresponding XRD pattern for IrCo0.65 NDs, and the bottoms are the corresponding standard values for Ir (black, PDF# 06-0598) and Co (red, PDF# 15-0806), respectively.

The high-resolution X-ray photoelectron spectroscopy (XPS) spectrum of the as-prepared IrCo0.65 NDs in Figure 2a shows the Ir 4f could be deconvoluted into four peaks, i.e., Ir0 4f7/2, Ir4+ 4f7/2, Ir0 4f5/2, and Ir4+ 4f5/2, which located at 60.66, 61.52, 63.69 and 64.72 eV, respectively.27 Among them, the intensities of Ir0 peaks are much higher than that of Ir4+ peaks, indicating the successful formation of metallic Ir. The spectrum of Co 2p locating at 778.6 and 781.6 eV are


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assigned to characteristic peaks of metallic and oxidative state of Co 2p3/2, respectively (Figure 2b). The peaks locating at 793.7 and 796.9 eV are attributed to the metallic and oxidative state of Co 2p1/2, respectively.28 The oxidative state of Co 2p might be resulted from surface oxidation under the air atmosphere.28 There are also two shakeup satellite peaks of Co 2p3/2 and Co 2p1/2 located at around 786.3 and 802.8 eV, respectively. Compared with the standard situations of Ir 4f peak and Co 2p peak, the Ir 4f peak of IrCo0.65 has negatively moved about 0.2 eV while the Co 2p peak positively moved about 0.3 eV, further indicating the successful formation of IrCo alloy with strong electron interactions between Ir and Co at the atomic lever.29, 30

Figure 2. XPS spectra for IrCo0.65 NDs: Ir 4f (a), Co 2p (b).

To get further insight into the evolution, the effects of various experimental parameters on the unique architecture were studied. We found the feeding ratios of Ir and Co precursors and the reaction solvents are very important for the formation of unique petal-like nanodendrites. Based on the results of ICP-AES, we specified the other two IrCo alloys with different initial molar


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ratios of Ir and Co as IrCo1.48 and IrCo2.71, respectively. TEM images of IrCo1.48 and IrCo2.71 were shown in Figure S1. It’s clear to see that the morphologies differed with the feeding ratios of precursors, which varied from nanodendrites to nanospheres with the decreasing mole ratios of Ir/Co precursors. Specifically, the structure of IrCo1.48 emerges the feature of nanospheres with a mean grain size of about 21 nm (Figure S1a and b). Further increasing the amount of Co precursor, the morphology of nanospheres becomes inhomogeneous with different size of nanospheres, suggesting that phase separation might have occurred (Figure S1c and d). In addition, EDX spectra shown in Figure S2 imply that the corresponding atomic ratios of Ir and Co are agree well with the ICP results. In Figure S3, XRD patterns display the peaks at 41.8°and 71.2°become both wider and the shoulder peaks located at 48.3°are almost disappeared, with the increasing amount of Co precursor. Furthermore, an obvious phase separation has occurred in the pattern of IrCo2.71 with additional peaks corresponding well with face-centered cubic (fcc) Co, suggesting IrCo alloy and Co nanoparticles were coexistent. We also studied the effect of solvent on the features of IrCo. As shown in Figure S4, adding small amount of 1-octadecene (ODE) to maintain volume ratio of OAm/ODE at 5/1, the morphology of nanodendrites still maintained except for the much smaller diameter (12.5 nm) (Figure S4a and b). However, some impurities of spheres are observed. Further increase the volume proportion of OAm/ODE to 3/3, spherical nanoparticles with an average diameter of 4.8 nm are observed (Figure S4c and d). The corresponding XRD patterns shown in Figure S5 indicate the formation of IrCo alloys. However, as shown in Figure S6, only irregular nanoparticles of 1.9 nm in diameter are obtained in pure ODE without the addition of OAm. The XRD peaks are mainly in line with the planes of fcc Ir, suggesting that only Ir nanoparticles are formed.


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The as-synthesized catalysts were first loaded on XC-72 to evaluate their electrocatalytic performances. For comparison, Ir nanodendrites were also synthesized using the similar method without adding Co precursor. The corresponding characterizations displayed in Figure S7 suggest the successful synthesis of Ir. In addition, the catalytic performances of commercial Pt/C and IrO2 were investigated as well. HER performances of as-prepared catalysts in 0.1 M HClO4 electrolyte are exhibited in Figure 3a. At 10 mA cm-2, IrCo0.65 NDs exhibit the highest activity (17 mV vs. RHE), even better than that of Pt/C (18 mV vs. RHE), and smaller than those of Ir (28 mV vs. RHE), IrCo1.48 (27 mV vs. RHE) and IrCo2.71 (24 mV vs. RHE). Corresponding Tafel slopes are presented in Figure 3b. IrCo0.65 NDs exhibit the lowest Tafel slope of 35.3 mV dec-1 within the as-synthesized IrCo alloys and Ir, comparable to Pt/C (31.2 mV dec-1). It is worth noting the catalytic performance of IrCo0.65 NDs is among top of the reported catalysts, making IrCo0.65 NDs among the most active electrocatalysts toward acidic HER (Table S1). Accelerated degradation test and chronopotentiometric method were also studied to examine the stability of IrCo0.65 NDs. The HER polarization curves are almost maintained well before and after 500 cycles (Figure 3c). Moreover, the overpotential emerged a negligible change after continuous operation for 20000 s at 10 mA cm-2 (Figure 3d). For comparison, stabilities for IrCo1.48 and IrCo2.71 were also investigated, which still show negligible variation in acidic condition (Figure S8). After stability test of IrCo0.65 NDs, TEM image shown in Figure S9a indicates the nanodendrites with petal-like structure are almost maintained well. In addition, the peaks in XRD pattern still represented the existence of IrCo alloy (Figure S9b), indicating the superior stability of IrCo0.65 NDs toward HER in a long-term electrochemical process in acid media.


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Figure 3. HER performance in 0.1 M HClO4 solution: (a) polarization curves of IrCo0.65, IrCo1.48, IrCo2.71, Ir and Pt/C; (b) Tafel slopes of IrCo0.65, IrCo1.48, IrCo2.71, Ir and Pt/C; (c) LSV curves of IrCo0.65 at the initial and after 500 cycles; (d) Chronopotentiometry measurement for IrCo0.65 at 10 mA cm-2.

OER performance of as-synthesized IrCo alloys were also examined in 0.1 M HClO4. Figure 4a shows IrCo0.65 NDs exhibit the highest catalytic activity (281 mV vs. RHE) at 10 mA cm-2, much lower than those of IrO2 (320 mV vs. RHE), Ir (310 mV vs. RHE), IrCo1.48 (298 mV vs. RHE), and IrCo2.71 (291 mV vs. RHE). The corresponding Tafel slope for IrCo0.65 NDs is 59.3 mV dec-1, much smaller than IrO2 (67.3 mV dec-1), further suggesting outstanding catalytic activity of IrCo0.65 NDs (Figure 4b). For the accelerated degradation test, the polarization curves of IrCo0.65 NDs are maintained well before and after 500 cycles (Figure 4c). Furthermore, after conducting for 20000 s, no obvious change is observed, further indicating superior stability of


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OER in acid electrolyte (Figure 4d). Likewise, IrCo1.48 and IrCo2.71 both exhibit excellent durability under the same operate condition (Figure S10). TEM image of IrCo0.65 NDs after OER test suggests that the nanodendrites are still uniform dispersed and the whole morphologies are almost unchanged (Figure S11a). Furthermore, the XRD patterns confirm the alloy feature of IrCo is maintained well (Figure S11b). In order to figure out the real surface chemical states of IrCo0.65 NDs during the OER catalysis, IrCo0.65 NDs after stability test in 0.1 M HClO4 electrolyte was further collected and characterized by XPS. Surface oxidation of Ir has occurred after OER test based on positively moved position of Ir 4f peak (Figure S12).18-20 However, the peak of Co 2p almost disappeared after conducting in acid solution due to the inevitable metal etching on the surface of the catalyst.27 Thus, the formation of IrOx species on the surface might be imperative for the superior catalytic performance of IrCo0.65 NDs.20

Figure 4. OER performance in 0.1 M HClO4 solution: (a) polarization curves of IrCo0.65, IrCo1.48, IrCo2.71, Ir and IrO2; (b) Tafel slopes of IrCo0.65, IrCo1.48, IrCo2.71, Ir and IrO2; (c) LSV curves of


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IrCo0.65 at the initial and after 500 cycles; (d) Chronopotentiometry measurement for IrCo0.65 at 10 mA cm-2.

In addition, specific surface areas for the superior catalytic performance of IrCo0.65 over IrCo1.48 and IrCo2.71 were explored via electrochemical double layer capacitance (Cdl). Figure S13 shows that the Cdl of IrCo0.65 is much higher than those of IrCo1.48 and IrCo2.71, suggesting the larger specific surface area of IrCo0.65 nanodendrites with anisotropic architecture. In view of superior HER and OER performances of IrCo0.65 NDs in acidic solution, we built an acidic water splitting electrolyzer using IrCo0.65 NDs as both anode and cathode catalyst. For comparison, Pt/C and IrO2 were also tested. Figure 5 demonstrates corresponding polarization curves and durability test for water electrolysis. During the catalytic process, IrCo0.65 NDs deliver a cell voltage of 1.593 V at 10 mA cm-2, comparable to Pt/C-IrO2 (1.58 V). After continuous operation for 20000 s, the performance is remained virtually steady at the fixed current density. In addition, the as-prepared Ir nanodendrite has also been tested for acidic water electrolysis. In Figure S14, Ir NDs shows a much lower cell voltage of 1.62 V at 10 mA cm-2. In addition, the molar ratio of gases (H2 and O2) released is measured around 2, suggesting the Faraday efficiency is nearly 100% at 100 mA (Figure S15).


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Figure 5. Water electrolysis in 0.1 M HClO4 electrolyte: (a) Polarization curves of IrCo0.65 and Pt/C (cathode)-IrO2 (anode); (b) Chronopotentiometry measurement of IrCo0.65 at 10 mA cm-2.

In conclusion, we demonstrate a general colloidally synthetic method for preparing IrCo nanodendrites with petal-like morphology. We find that the molar ratios of Ir/Co precursors and reaction solvent are essential for the formation of IrCo alloy with this unique architecture. As expected, by taking advantage of this unique anisotropic morphology, which offering more active sites exposure and facilitating mass/charge transfer, facile release of evolved gases in catalysis, and strong synergistic electronic interaction between Ir and Co, the as-obtained IrCo0.65 NDs exhibit much higher electrocatalytic performance for HER and OER in 0.1 M HClO4. To achieve 10 mA cm-2, the overpotentials are respectively 17 and 281 mV. When used to electrolyze acidic water splitting, IrCo0.65 NDs demonstrate a low cell voltage of 1.593 V at 10 mA cm-2. This study highlights a new strategy to fabricate high-performance electrocatalysts toward acidic overall water splitting, and might suggest a novel way for practical application in proton exchange membrane (PEM) electrolyzers.


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ASSOCIATED CONTENT Supporting Information. The following files are available free of charge. Experimental details and Supplementary material of characterization method, Faraday efficiency, Table S1.

AUTHOR INFORMATION Corresponding Author * E-mail: [email protected] Author Contributions L. Fu and X. Zeng prepared the IrCo alloy nanodendrites and evaluated their electrochemical performances. L. Fu characterized the IrCo alloy nanodendrites and analyzed the experimental results. The manuscript was written by L. Fu with contributions from all other authors. Notes The authors declare no competing financial interest. ACKNOWLEDGMENT Thanks for the supporting of the National Natural Science Foundation of China (21571145, 21633008), and Large-scale Instrument and Equipment Sharing Foundation of Wuhan University.


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REFERENCES (1) Liu, J.; Liu, Y.; Liu, N.; Han, Y.; Zhang, X.; Huang, H.; Lifshitz, Y.; Lee, S.-T.; Zhong, J.; Kang, Z. Metal-free efficient photocatalyst for stable visible water splitting via a twoelectron pathway. Science. 2015, 347, 970-974. (2) Hunter, B. M.; Gray, H. B.; Müller, A. M. Earth-abundant heterogeneous water oxidation catalysts. Chem. Rev. 2016, 116, 14120-14136. (3) Wu, C.; Liu, D.; Li, H.; Li, J. Molybdenum Carbide-Decorated Metallic Cobalt@Nitrogen-Doped Carbon Polyhedrons for Enhanced Electrocatalytic Hydrogen Evolution. Small 2018, 14, 1704227. (4) Zhang, G.; Wang, G.; Liu, Y.; Liu, H.; Qu, J.; Li, J. Highly active and stable catalysts of phytic acid-derivative transition metal phosphides for full water splitting. J. Am. Chem. Soc. 2016, 138, 14686-14693. (5) Xu, X.; Du, P.; Chen, Z.; Huang, M. An electrodeposited cobalt-selenide-based film as an efficient bifunctional electrocatalyst for full water splitting. J. Mater. Chem. A 2016, 4, 10933-10939. (6) Zhu, W.; Yue, Z.; Zhang, W.; Hu, N.; Luo, Z.; Ren, M.; Xu, Z.; Wei, Z.; Suo, Y.; Wang, J. Wet-chemistry topotactic synthesis of bimetallic iron-nickel sulfide nanoarrays: an advanced and versatile catalyst for energy efficient overall water and urea electrolysis. J. Mater. Chem. A 2018, 6, 4346-4353.


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Page 15 of 19 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


(7) Zhu, W.; Yue, X.; Zhang, W.; Yu, S.; Zhang, Y.; Wang, J.; Wang, J. Nickel sulfide microsphere film on Ni foam as an efficient bifunctional electrocatalyst for overall water splitting. Chem. Commun. 2016, 52, 1486-1489. (8) Zhu, W.; Liu, L.; Yue, Z.; Zhang, W.; Yue, X.; Wang, J.; Yu, S.; Wang, L.; Wang, J. Au Promoted Nickel-Iron Layered Double Hydroxide Nanoarrays: A Modular Catalyst Enabling High-Performance Oxygen Evolution. ACS Appl. Mater. Interfaces 2017, 9, 19807-19814. (9) Zhu, W.; Tang, C.; Liu, D.; Wang, J.; Asiri, A. M.; Sun, X. A self-standing nanoporous MoP2 nanosheet array: an advanced pH-universal catalytic electrode for the hydrogen evolution reaction. J. Mater. Chem. A 2016, 4, 7169-7173. (10) Zhang, H.; Shen, P. K. Recent development of polymer electrolyte membranes for fuel cells. Chem. Rev. 2012, 112, 2780-2832. (11) Durst, J.; Siebel, A.; Simon, C.; Hasché, F.; Herranz, J.; Gasteiger, H. A. New insights into the electrochemical hydrogen oxidation and evolution reaction mechanism. Energy Environ. Sci. 2014, 7, 2255-2260. (12) Seitz, L. C.; Dickens, C. F.; Nishio, K.; Hikita, Y.; Montoya, J.; Doyle, A.; Kirk, C.; Vojvodic, A.; Hwang, H. Y.; Norskov, J. K.; Jaramillo, T. F. A highly active and stable IrOx/SrIrO3 catalyst for the oxygen evolution reaction. Science 2016, 353, 1011-1014. (13) Oh, H.-S.; Nong, H. N.; Reier, T.; Bergmann, A.; Gliech, M.; de Ara´ujo, J. F.; Willinger, E.; Schlögl, R.; Teschner, D.; Strasser, P. Electrochemical Catalyst–Support Effects and


15


Page 16 of 19

Their Stabilizing Role for IrOx Nanoparticle Catalysts during the Oxygen Evolution Reaction. J. Am. Chem. Soc. 2016, 138, 12552-12563. (14) Lettenmeier, P.; Wang, L.; Golla-Schindler, U.; Gazdzicki, P.; Canas, N. A.; Handl, M.; Hiesgen, R.; Hosseiny, S. S.; Gago, A. S.; Friedrich, K. A. Nanosized IrOx-Ir Catalyst with Relevant Activity for Anodes of Proton Exchange Membrane Electrolysis Produced by a Cost‐Effective Procedure. Angew. Chem., Int. Ed. 2016, 55, 742-746. (15) Pi, Y.; Shao, Q.; Wang, P.; Guo, J.; Huang, X. General formation of monodisperse IrM (M= Ni, Co, Fe) bimetallic nanoclusters as bifunctional electrocatalysts for acidic overall water splitting. Adv. Funct. Mater. 2017, 27, 1700886. (16) Reier, T.; Pawolek, Z.; Cherevko, S.; Bruns, M.; Jones, T.; Teschner, D.; Selve, S.; A.; Nong, H. N.; Schlögl, R.; Mayrofer, K. J. J.; Strasser, P. Molecular insight in structure and activity of highly efficient, low-Ir Ir-Ni oxide catalysts for electrochemical water splitting (OER). J. Am. Chem. Soc. 2015, 137, 13031-13040. (17) Zhang, Y.; Wu, C.; Jiang, H.; Lin, Y.; Liu, H.; He, Q.; Chen, S.; Duan, T.; Song, L. Atomic Iridium Incorporated in Cobalt Hydroxide for Efficient Oxygen Evolution Catalysis in Neutral Electrolyte. Adv. Mater. 2018, 30, 1707522. (18) Pi, Y.; Zhang, N.; Guo, S.; Guo, J.; Huang, X. Ultrathin laminar Ir superstructure as highly efficient oxygen evolution electrocatalyst in broad pH range. Nano Lett. 2016, 16, 4424-4430.


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Page 17 of 19 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


(19) Feng, J.; Lv, F.; Zhang, W.; Li, P.; Wang, K.; Yang, C.; Wang, B.; Yang, Y.; Zhou, J.; Lin, F.; Wang, G.-C.; Guo, S. Iridium-Based Multimetallic Porous Hollow Nanocrystals for Efficient Overall-Water-Splitting Catalysis. Adv. Mater. 2017, 29, 1703798. (20) Kwon, T.; Hwang, H.; Sa, Y. J.; Park, J.; Baik, H.; Joo, S. H.; Lee, K. Cobalt Assisted Synthesis of IrCu Hollow Octahedral Nanocages as Highly Active Electrocatalysts toward Oxygen Evolution Reaction. Adv. Funct. Mater. 2017, 27, 1604688. (21) Alia, S. M.; Shulda, S.; Ngo, C.; Pylypenko, S.; Pivovar, B. S. Iridium-based Nanowires as Highly Active, Oxygen Evolution Reaction Electrocatalysts. ACS Catal. 2018, 8, 2111-2120. (22) Lim, J.; Park, D.; Jeon, S. S.; Roh, C.-W.; Choi, J.; Yoon, D.; Park, M.; Jung, H.; Lee, H. Ultrathin IrO2 Nanoneedles for Electrochemical Water Oxidation. Adv. Funct. Mater. 2018, 28, 1704796. (23) Yu, A.; Lee, C.; Kim, M. H.; Lee, Y. Nanotubular Iridium-Cobalt Mixed Oxide Crystalline Architectures Inherited from Cobalt Oxide for Highly Efficient Oxygen Evolution Reaction Catalysis. ACS Appl. Mater. Interfaces 2017, 9, 35057-35066. (24) Fu, L.; Yang, F.; Cheng, G.; Luo, W. Ultrathin Ir nanowires as high-performance electrocatalysts for efficient water splitting in acidic media. Nanoscale 2018, 10, 18921897. (25) Fu, L.; Cheng, G.; Luo, W. Colloidal synthesis of monodisperse trimetallic IrNiFe nanoparticles as highly active bifunctional electrocatalysts for acidic overall water splitting. J. Mater. Chem. A 2017, 5, 24836-24841.


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Page 18 of 19

(26) Lim, B.; Jiang, M.; Camargo, P. H. C.; Cho, E. C.; Tao, J.; Lu, X.; Zhu, Y.; Xia, Y. Pd-Pt bimetallic nanodendrites with high activity for oxygen reduction. Science 2009, 324, 1302-1305. (27) Park, J.; Sa, Y. J.; Baik, H.; Kwon, T.; Joo, S. H.; Lee, K. Iridium-Based Multimetallic Nanoframe @ Nanoframe Structure: An Efficient and Robust Electrocatalyst toward Oxygen Evolution Reaction. ACS Nano 2017, 11, 5500-5509. (28) Jin, H.; Wang, J.; Su, D.; Wei, Z.; Pang, Z.; Wang, Y. In situ cobalt-cobalt oxide/Ndoped carbon hybrids as superior bifunctional electrocatalysts for hydrogen and oxygen evolution. J. Am. Chem. Soc. 2015, 137, 2688-2694. (29) E, B.; Shao, Q.; Bu, L.; Bai, S.; Li, Y.; Huang, X. Ordered PtPb/Pt Core/Shell Nanodisks as Highly Active, Selective, and Stable Catalysts for Methanol Reformation to H2. Adv. Energy Mater. 2018, 8, 1703430. (30) Liu, Y.; Liu, S.; Che, Z.; Zhao, S.; Sheng, X.; Han, M.; Bao, J. Concave octahedral Pd@PdPt electrocatalysts integrating core-shell, alloy and concave structures for highefficiency oxygen reduction and hydrogen evolution reactions. J. Mater. Chem. A 2016, 4, 16690-16697.


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IrCo nanodendrite as an efficient bifunctional electrocatalyst for overall

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