Achieving Overall Carbon Utilization from Organic Wastewater to Recover Solar Syngas via an Artificial Carbon Cycling System

Abstract

AbstractBuilding artificial carbon cycling systems for the direct conversion of wastewater into value‐added solar fuels using renewable solar energy can contribute to achieving carbon neutrality. Herein, a bifunctional photocatalyst comprising three‐dimensionally ordered Ti3C2Tx/TiO2 nanoflowers is exploited for tandem carbon cycling systems to achieve efficient organic wastewater treatment with simultaneous CO2 resourcing. The highest efficiency is achieved by using the optimal Ti3C2Tx/TiO2 photocatalyst to treat simulated wastewater containing rhodamine B (RhB), with an enhanced primary CO production rate of 10.02 µmol g−1 h−1 and RhB degradation efficiency of 77.6% after 1 h of illumination in an anoxic environment. The CO/H2 ratio of the produced syngas can be readily tuned from 0.95 to 1.86 by adjusting the Ti3C2Tx content. Mechanistic studies based on DFT, in situ DRIFTS, and LC‐MS2/IC reveal that the coupled photocatalytic RhB degradation and CO2 reduction processes collectively undertake *HCOO intermediate coverage. This phenomenon triggers the sustainable and simultaneous conversion of *CO2 and *HCOO into CO under mild conditions and crosses the key rate‐limiting step of CO2‐to‐CO conversion, thereby achieving overall carbon utilization from organic wastewater treatment. This study offers in‐depth insights into the design and mechanisms of highly effective carbon utilization in artificial carbon cycling systems.