Bimetal-modified g-C3N4 photocatalyst for promoting hydrogen production coupled with selective oxidation of biomass derivative

Abstract

The solar-driven coproduction of hydrogen (H2) fuel and value-added chemicals from biomass derivatives represents a promising strategy to address the energy and environment issues. Herein, the Ni-Au bimetal modified g-C3N4 photocatalyst was synthesized by a step-by-step photodeposition method and used to promote the photocatalytic coproduction of H2 and furfural from furfural-alcohol aqueous solution. In the designed Ni-Au/g-C3N4 photocatalyst, g-C3N4 was the main light-harvesting material for generating electron-hole pairs which were separated efficiently by metal/g-C3N4 interface, plasmonic Au nanoparticles further increased the light utilization efficiency, and Ni acted as both electron trap and the active sites for H2 evolution. Beneficial from the synergy of three components, the Ni-Au/g-C3N4 photocatalyst exhibited 3-folds activity of Au/CN sample toward photocatalytic coproduction of H2 and furfural. Both photoluminescence spectroscopy and photoelectrochemical measurements demonstrated the more efficient separation and transfer of photogenerated charge carriers in Ni-Au/g-C3N4 photocatalyst. In situ electron spin resonance revealed the generations of hydroxyl radical and carbon center radical in the photocatalytic reaction. Based on the systematic characterizations, a photocatalytic mechanism was proposed and discussed. This work provides a rational construction of photocatalysts for coproduction of H2 and value-added chemicals from biomass derivatives as well as explores the synergistic effect of bimetallic cocatalyst on enhancing the photocatalysis.