Abstract
The construction of Z-scheme photocatalyst has been verified to be an effective route to develop high-efficiency visible-light composite photocatalysts. In this study, we designed a highly efficient Z-scheme Cu2O-rGO-CuO composite photocatalyst by using rGO as a solid electron mediator. The Cu2O-rGO-CuO composites were synthesized via a facile two-step method, including the initial grafting of rGO on the Cu2O surface and then in situ deposition of CuO nanoparticles on the Cu2OrGO surface. It was found that all the resulted Cu2O-rGO-CuO photocatalysts showed a much higher photocatalytic activity than the single-component (Cu2O) or two-component (such as Cu2O-rGO and Cu2O-CuO) photocatalysts, and the Cu2O-rGO-CuO (0.5 wt%) showed the highest performance (k = 0.033 min-1), obviously higher than that of Cu2O-rGO (0.014 min-1) and Cu2O-CuO (0.010 min-1) photocatalysts. Based on the experimental results and energy band structures of Cu2O and CuO, a possible mechanism of Z-scheme Cu2O-rGO-CuO photocatalytic system was proposed to account for their enhanced photocatalytic performance. The enhanced photocatalytic activity can be ascribed the efficient electron transfer in Cu2O-rGO-CuO Z-scheme system via rGO as a new and effective electron mediator. Compared with the wellknown electron mediators such as Au, Ag, and Pt, the present promising graphene nanosheets with large specific surface area and high electroconductivity can be regarded as an ideal solid-state electron mediator for the design and development of various Z-scheme photocatalysts.
Keywords: Cu2O-rGO-CuO, electron mediator, graphene, Z-scheme.
Graphical Abstract
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