Graphene-wrapped Pt/TiO 2 photocatalysts with enhanced photogenerated charges separation and reactant adsorption for high selective photoreduction of CO 2 to CH 4

Abstract Artificial photosynthesis efficiency for selective CO 2 conversion to CH 4 as chemical energy-rich molecule is dependent on the photogenerated charges separation and reactant adsorption property of photocatalyst. Here we report a novel fabrication of core-shell-structured photocatalysts of Pt/TiO 2 -nanocrystals wrapped by reduced graphene oxide (rGO) sheets ((Pt/TiO 2 )@rGO). The ultrafine anatase TiO 2 nanocrystals with coexposed {001} and {101} facets acted as the fountain of the photogenerated charges primitively. Pt nanoparticles (NPs) deposited on the TiO 2 nanocrystals can gather and transfer the stimulated electrons originated from anatase TiO 2 nanocrystals. The all-solid-state electron multiple transmission (EMT) system with TiO 2 -nanocrystal(core)-Pt(mediator)-rGO(shell) nanojunction is not only favorable to the vectorial electron transfer of TiO 2  → Pt → rGO and enhance the separation efficiency of photogenerated electrons and holes, but also the surface residual hydroxyl and extended π bond of wrapping rGO sheets can improve the adsorption and activation capabilities for CO 2 reactant. (Pt/TiO 2 )@rGO ternary photocatalysts exhibit excellent performance for the multi-electron process of selective photocatalytic CO 2 conversion to CH 4 . Among the prepared catalysts, (Pt/TiO 2 )@rGO-2 catalyst shows the highest photocatalytic activity and selectivity for CO 2 conversion, i.e., the formation rate of CH 4 is 41.3 μmol g −1  h −1 and the selectivity of CO 2 conversion to CH 4 product is 99.1%, and its apparent quantum efficiency for CH 4 product is 1.93%. As a heuristic the fabrication of core-shell structured (Pt/TiO 2 )@rGO photocatalysts will stimulate more novel ideas for application to light-chemical energy conversion.