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. Ni_xS_y-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