Bi₃O₄Cl/g-C₃N₄/Cd_0.5Zn_0.5S Double Z-Scheme Heterojunction Photocatalyst for Highly Selective CO₂ Reduction to Methane

Abstract

Solar-energy-driven CO2 hydrogenation is a promising strategy to alleviate the climate crisis. Methane is a desirable derivative of CO2 reduction. However, developing a photocatalyst for highly active and selective CH4 generation remains challenging. Herein, we report a double Z-scheme Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S photocatalyst for efficient reduction of CO2 to CH4. In situ characterization techniques confirmed that the charge migration mechanism in Bi3O4Cl/g-C3N4/Cd0.5Zn0.5S promotes charge separation through double internal electric fields. As a result, the optimized C0.01B0.02C catalyst displayed a formation rate high up to 25.34 μmol g–1 h–1 and a selectivity of 96.52% of CH4. Moreover, the AQY of CO2 conversion on C0.01B0.02C (1.84%) was almost 41 times higher than that of the bare CN. This study provides a novel perspective to develop heterojunction photocatalysts for selective CO2 conversion to CH4.

Construction of an In2O3/Bi2S3 Z-Scheme Heterojunction for Enhanced Photocatalytic CO2 Reduction

“…Fossil energy has greatly contributed to the rapid development of human society, which is being depleted, and the burning of these fossil fuels causes dramatically increased CO 2 concentrations in the air, leading to the undesirable greenhouse effect. − Thus, exploiting sustainable clean energy and reducing CO 2 emissions are the most urgent and important targets today . Driven by endless solar energy, the conversion of CO 2 to hydrocarbon fuel, including carbon monoxide (CO), methanol (CH 3 OH), methane (CH 4 ), formic acid (HCOOH), and ethane (C 2 H 6 ), over semiconductor photocatalysts, is regarded as a potential technology to simultaneously address the above two problems. − However, the current photocatalytic CO 2 reduction systems suffer from low efficiency, which is mainly ascribed to the limited photoresponse range and inefficient charge separation. − Therefore, developing efficient and stable photocatalysts with visible-light absorption for CO 2 conversion is crucial for their utilization in practical applications …”