Improved visible-light photoactivity of Pt/g-C3N4 nanosheets for solar fuel production via pretreated boric acid modification

Abstract

In this work, the photocatalytic activities of g-C3N4 nanosheets for CO2 conversion and H2 production were obviously promoted by modifying an appropriate amount of Pt as the photoelectron-acceptor and co-catalyst. The optimized 0.5Pt–CN displayed ~ 2-times higher photocatalytic activities for both CO2 reduction and H2 production than those of bare CN nanosheets. Importantly, the photocatalytic activities for solar fuel production of Pt–g-C3N4 nanosheets can be further enhanced by pretreating a suitable amount of boric acid modification on g-C3N4 nanosheets. Compared to 0.5Pt–CN and bare CN, the optimized 0.5Pt–5B–CN (5% boric acid in molar ratios) displayed ~ 2- and 9-times enhancement for reducing CO2 to CO, as well as CH4 while ~ 2- and 10-times enhancement for H2 production, respectively. By means of the steady-state surface photovoltage spectra, fluorescence spectra and fluorescence spectra related to the produced ·OH amount, the exceptional photoactivities were comprehensively attributed to the boric acid-assisted high dispersion of Pt on g-C3N4 nanosheet which enhances the charge separation and improves the co-catalytic activity. This pretreated boric acid modification strategy is also applicable for other noble metals like Ag and Au. This work provides a new strategy on developing an efficient g-C3N4-based photocatalyst for solar fuel production.