Rationally designed plasmonic hybrid coupling structure of Ag/rGO-ZnO for enhanced photocatalytic CO2 reduction

Abstract

In this work, a plasmonic hybrid coupling-enhanced photocatalyst of Ag/rGO (reduced graphene oxide)-ZnO, integrating superior activity, lasting stability, and low cost all-in-one, is proposed to settle limitations related to narrow photoresponse range and high charge recombination on ZnO. Graphene oxide nanoflakes were successfully composited with ZnO nanorods using the self-assembly method, then modified with Ag nanoparticles. UV–vis absorption spectra, photoelectrochemical characterizations and the finite difference time domain simulations show that this nanocomposite has enhanced catalytic activity for reducing CO2 to CO and CH4 compared to pure ZnO (P-ZnO). By tuning the content of graphene and Ag, the maximum photocatalytic efficiency of Ag/rGO-ZnO (62.7 μmol g−1 h−1) far exceeds that of P-ZnO by at least 28 times, with high stability for more than 24 h in the absence of hole scavengers and photosensitizers. Meanwhile, with the addition of Ag and graphene, Ag/rGO-ZnO exhibits a selective tendency toward the cleaner fuel-CH4, which is 7 times higher than P-ZnO. Our study highlights the potential of broadening the light response range, suppressing e−/h+ recombination, and improving the stability of catalysts based on a nanocomposite structure. It also provides a more valuable reference for promoting low-cost commercial applications of ZnO photocatalysts.