Enhanced Photocatalytic Hydrogen Evolution of NiCoP/g-C3 N4 with Improved Separation Efficiency and Charge Transfer Efficiency.

Although NiCoP has attracted much attention in the field of electrocatalysis, the study of its photocatalytic activity and mechanism have been somewhat limited. NiCoP/g-C3 N4 , synthesized by simple one-pot method, is a highly efficient photocatalyst for hydrogen production from water. NiCoP/g-C3 N4 exhibits a hydrogen evolution rate of 1643 μmol h-1  g-1 , which is 21 times higher than that of bare g-C3 N4 . The excellent performance is due to a combination of improved separation efficiency and effective charge transfer efficiency. The photogenerated charge behavior is characterized by the surface photovoltage (SPV), transient photovoltage (TPV), and photoluminescence spectroscopy. The photogenerated charge transport is investigated by electrochemical impedance spectroscopy and polarization curve. Moreover, the effective charge transfer efficiency was measured according to the mimetic apparent quantum yield. SPV and TPV measurements, whereby 10 vol % of a triethanolamine-water mixture was added into the testing system, were taken to simulate the real atmosphere for photocatalytic reaction, which can give rise to the photogenerated charge transfer process. A possible photocatalytic mechanism was also proposed. This study may provide an efficient theoretical basis to design transition metal phosphide cocatalyst-modified photocatalysts.