Photoelectrochemical （PEC） water splitting is a promising approach to harvest and store solar energy [1]. Silicon has been widely investigated for PEC photoelectrodes due to its suitable band gap （1.12 eV） matchin...Photoelectrochemical （PEC） water splitting is a promising approach to harvest and store solar energy [1]. Silicon has been widely investigated for PEC photoelectrodes due to its suitable band gap （1.12 eV） matching the solar spectrum [2]. Here we investigate employing nickel both as a catalyst and protecting layer of a p-type silicon photocathode for photoelectrochemical hydrogen evolution in basic electrolytes for the first time. The silicon photocathode was made by depositing 15 nm Ti on a p-type silicon wafer followed by 5 nm Ni. The photocathode afforded an onset potential of -0.3 V vs. the reversible hydrogen electrode （RHE） in alkaline solution （1 M KOH）. The stability of the Ni/Ti/p-Si photocathode showed a 100 mV decay over 12 h in KOH, but the stability was significantly improved when the photocathode was operated in potassium borate buffer solution （pH ≈ 9.5）. The electrode surface was found to remain intact after 12 h of continuous operation at a constant current density of 10 mA/cm^2 in potassium borate buffer, suggesting that Ni affords good protection of Si based photocathodes in borate buffers.展开更多
文摘Photoelectrochemical （PEC） water splitting is a promising approach to harvest and store solar energy [1]. Silicon has been widely investigated for PEC photoelectrodes due to its suitable band gap （1.12 eV） matching the solar spectrum [2]. Here we investigate employing nickel both as a catalyst and protecting layer of a p-type silicon photocathode for photoelectrochemical hydrogen evolution in basic electrolytes for the first time. The silicon photocathode was made by depositing 15 nm Ti on a p-type silicon wafer followed by 5 nm Ni. The photocathode afforded an onset potential of -0.3 V vs. the reversible hydrogen electrode （RHE） in alkaline solution （1 M KOH）. The stability of the Ni/Ti/p-Si photocathode showed a 100 mV decay over 12 h in KOH, but the stability was significantly improved when the photocathode was operated in potassium borate buffer solution （pH ≈ 9.5）. The electrode surface was found to remain intact after 12 h of continuous operation at a constant current density of 10 mA/cm^2 in potassium borate buffer, suggesting that Ni affords good protection of Si based photocathodes in borate buffers.
