NiMo Catalyst Electrodeposited on Si Photocathodes for Enhanced Solar Water Splitting

NiMo合金最近作为电解水制氢催化剂得到了较多的研究，但其担载在光解水光阴极上的催化作用则研究较少。本文以稳定性较好的2纳米Al2O3保护的单晶n+p-Si光阴极为基础，利用电沉积方法在其表面制备了NiMo催化剂，研究其光催化活性。通过多次间断电沉积及测试光阴极光电化学特性，确定了最优的NiMo量。在偏中性的邻苯二甲酸氢钾电解液中及100 mW•cm−2 Xe灯照射下，NiMo/Al2O3/n+p-Si光阴极的光电化学活性与对应的Pt/Al2O3/n+p-Si比较接近，开启电压达到0.5 V (vs. RHE)，光电流在0 V (vs. RHE)处达到了−32 mA•cm−2。本文也详细研究了不同pH值电解液中光阴极的光电化学稳定性，结果显示NiMo在碱性电解液中的表现最佳，而在酸性溶液中其很快会被腐蚀。 Recently, NiMo alloy has received lots of attention for the electrochemical catalyst in water split-ting. However, fewer works studied its catalytic effect on the photoelectrochemical (PEC) reactivity when it is loaded on a photocathode. In this study, we loaded the NiMo alloy on a stable 2 nm Al2O3 protected n+p-Si photocathode using electrodeposition method to explore its PEC catalytic effect. We determined the best amount of NiMo through interrupted electrodeposition and testing of PEC properties. In KHP electrolyte with pH = 4.5 and under the 100 mW•cm−2 Xe lamp illumination, the PEC reactivity of NiMo/Al2O3/n+p-Si is close to that of Pt/Al2O3/n+p-Si. Its on-set potential is 0.5 V (vs. RHE) and photocurrent at 0 V (vs. RHE) can be up to −32 mA•cm−2. We also studied its PEC stability when different electrolytes are used which have different pH values. NiMo is very stable in alkaline electrolyte; however, it is etched quickly in acid one.