In this study, ethanol is used as a solvothermal solvent to modify the surface properties of g-C₃N₄ for the first time. g-C₃N₄ is thermally treated in ethanol at different temperatures (T=140 ℃, 160 ℃, 180 ℃, and 220 ℃), and Pt cocatalyst is subsequently deposited on the g-C₃N₄ via a photoreduction method. Introduction of O-containing functional groups onto g-C₃N₄ was found to have a positive effect on the formation of Pt2+ species. XPS Pt 4f data display that the Pt2+/Pt0 value for the g-C₃N₄ treated at solvothermal temperature of 160 ℃ is the highest at 7.03, further showing the highest hydrogen production rate is at 492.3 μmol.g-1.h-1 since the PtO phase is favorable for the water adsorption and hydrogen desorption in the hydrogen evolution process.
As O-containing functional groups is influential in the Pt loading process and especially Pt2+ formation according to the aforementioned properties of solvothermally treated g-C₃N₄, a development of g-C₃N₄ modification and Pt decoration was studied to evaluate this metal-support interaction. A simple method is proposed to directly improve the metal-support interaction wherein the distribution and oxidation state of Platinum are controlled with the aid of O-containing functional groups on solvothermally treated g-C₃N₄ support, affording an enhanced photogenerated charge transfer and photocatalytic performance for H₂ evolution. As a result, the as-prepared photocatalyst exhibits a remarkably enhanced H₂ evolution rate under solar-simulated light, and the optimized 3Pt/SCN photocatalyst presents the outstanding HER activity at 1255.52 μmol.g-1.h-1, which is about 50 times higher than SCN photocatalyst (25.2 μmol.g-1.h-1). This facile approach provides a potential path to develop advanced photocatalysts for solar-simulated light-induced HER.