Highly Dispersed Pt Nanoparticle-Doped Mesoporous ZnO Photocatalysts for Promoting Photoconversion of CO2 to Methanol

Photoreduction of CO2 is considered a challenge due to the lack of effective photocatalysts with wide-spectrum absorption, active charge separation dynamically, and CO2 adsorption. Herein, mesoporous Pt/ZnO nanocomposites with different Pt percentages (0.5-2%) have been fabricated using the sol-gel process in the presence of a template for CO2 photoreduction during visible-light exposure. Pt nanoparticles (NPs) deposited onto mesoporous ZnO with a considerable surface area can effectively promote charge mobility. The mesoporous 1.5% Pt/ZnO nanocomposite exhibits an optimal CH3OH yield (668 mu mol g(-1)), which is 18.5-fold larger than that of mesoporous ZnO (36 mu mol g(-1)). The most photoactive material was the 1.5% Pt/ZnO nanocomposite, producing CH3OH of 668 mu mol g(-1), and the production rate of CH3OH over the 1.5% Pt/ZnO nanocomposite (74.11 mu mol g(-1) h(-1)) was increased 20 times in comparison with ZnO NPs (3.72 mu mol g(-1) h(-1)). The enhancement of CO2 photoreduction efficiency over Pt/ZnO nanocomposites was attributed to the formation of the heterojunction at the Pt/ZnO interface, promoting a lower resistance to charge transfer and a larger electron transfer to the conduction band. Mesoporous Pt/ZnO nanocomposites offer enhanced accessibility and a larger surface area. Such an unparalleled mesostructure provides a new framework for the construction and design of photoactive materials with high-efficiency photocatalysts.