Enhanced Electrocatalytic Activity of Sm2O3-doped Ni-Co Coating Electrode for Hydrogen Evolution Reaction

Direct electrochemical splitting of water is an attractive method to generate the renewable energy carrier hydrogen [1]. Low-cost catalyst for hydrogen evolution reaction (HER) is one key step in this process [2]. So far, there are no other pure metals except for noble elements really showing high activities for HER, and many efforts have been made to look for highly catalytic activated transition metal based alloys for HER [3,4]. In this work, HER was investigated on Ni-Co alloy electrode and Ni-Co-Sm2O3 composite electrode in 0.50 M Na2SO4 + 0.10 M H2SO4 solution. It was indicated that Sm2O3 particles promoted the formation of an amorphous structure of Ni-Co alloy coating, which was benefit for HER. The surface of Ni-Co-Sm2O3 composites was more coarse and grainy compared with that of Ni-Co alloy layer (Fig. 1). Steady-state polarization curves (Fig. 2) showed that the hydrogen evolution potential of Ni-Co-Sm2O3 composite electrode positively moved by about 240 mV at 8.0 mA cm-2 compared with that of Ni-Co alloy electrode, indicating that the embedded Sm2O3 particles enhanced the electrocatalytic activity of Ni-Co coating for HER. Furthermore, Ni-Co-Sm2O3 composite electrode has considerably lower charge transfer resistance and higher exchange current density. References [1] C. Lupi, A. Dell’Era, M. Pasquali. In situ activation with Mo of Ni-Co alloys for hydrogen evolution reaction. International Journal of Hydrogen Energy, 2014, 39: 1932-1940 [2] Wei Cui, Chenjiao Ge, Zhicai Xing, Abdullah M. Asiri, Xuping Sun. NixSy-MoS2 hybrid microspheres: One-pot hydrothermal synthesis and their application as a novel hydrogen evolution reaction electrocatalyst with enhanced activity. Electrochimica Acta, 2014, 137: 504–510 [3] Zhengwei Xie, Ping He, Licheng Du, Faqin Dong, Ke Dai, Tinghong Zhang. Comparison of four nickel-based electrodes for hydrogen evolution reaction. Electrochimica Acta, 2013, 88: 390-394 [4] Ping He, Xiaofang Yi, Yongjun Ma, Wei Wang, Faqin Dong, Licheng Du, Hongtao Liu. Effect of Gd2O3 on the hydrogen evolution property of nickel-cobalt coatings electrodeposited on titanium substrate, Journal of Physics and Chemistry of Solids, 2011, 72: 1261-1264 Figure 1