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

Highlights: • A hybrid Ag/rGO-ZnO photocatalyst settles limitations of poor photoresponse range and high charge recombination of ZnO. • The rationality of Ag/rGO-ZnO nanostructure is confirmed by PEC characterization and FDTD simulation. • Ag/rGO-ZnO shows enhanced CO₂ reduction activity and stability. -- 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.