An integrated photocatalytic redox architecture for simultaneous overall conversion of CO2 and H2O toward CH4 and H2O2
Muhammad Salman Nasir, Bowen Sheng, Ying Zhao, Haotian Ye, Jun Song, Jinglin Li, Ping Wang, Tao Wang, Xinqiang Wang, Zhen Huang, Baowen Zhou
Abstract
Solar-driven overall conversion of CO 2 and H 2 O into fuels and chemicals shows an ultimate strategy for carbon neutrality yet remains a huge challenge. Herein, an integrated photocatalytic redox architecture of Zn NPs/GaN Nanowires (NWs)/Si is explored for light-driven overall conversion of CO 2 and H 2 O into CH 4 and H 2 O 2 simultaneously without any external sacrificial agents and additives. The as-designed architecture affords a benchmark CH 4 activity of 189 mmol g cat −1 h −1 with a high selectivity of 93.6%, in the synchronized formation of H 2 O 2 at a considerable rate of 25 m g −1 h −1 . Moreover, a considerable turnover number of 27,280 mol CH 4 per mol Zn was achieved over a long-term operation of 80 h. By operando spectroscopic characterizations, isotope experiments, and density functional theory calculations, it is unraveled that Zn sites are synergetic with GaN to drive CO 2 -to-CH 4 conversion with a lowered energy barrier of 0.27 eV while inhibiting hydrogen evolution reaction with a relatively high energy barrier of 0.93 eV. Notably, owing to the unique surface properties of GaN, water is split into *OH and *H, followed by the formation of H 2 O 2 because of the alleviated adsorption strength of *OH by Zn NPs. Together, the hierarchical architecture enables the achievement of high activity and high selectivity of CH 4 from CO 2 reduction in distilled water along with the generation of H 2 O 2 . This work provides an integrated photocatalytic redox architecture for the synchronized production of CH 4 and H 2 O 2 with the only inputs of CO 2 , distilled water, and light.