Harnessing Photo‐to‐Thermal Conversion in Sulfur‐Vulcanized Mxene for High‐Efficiency Solar‐to‐Carbon‐Fuel Synthesis

Harnessing solar energy for the conversion of CO2 into value‐added chemicals and fuels represents a promising strategy for sustainable development. Photo‐to‐thermal (PTT) conversion, an often‐underestimated factor, offers a remarkable approach to enhance the photocatalytic transformation of CO2, by reducing the activation energy of catalytic reactions and accelerating reaction kinetics. In order to achieve a higher energy return on investment (EROI), in this study, a sulfur‐vulcanized, multi‐layer Ti3C2 MXene is unveiled, capable of efficient sunlight‐driven CO2 photoreduction, by capitalizing on PTT conversion across the full visible‐to‐near‐infrared (NIR) spectrum. The vulcanization strategy is pivotal here, as it not only introduces an abundance of reactive sites but also extends the NIR response (peaking at 1095 nm) of MXene. The resulting rapid PTT and synergistic photo‐thermal‐catalytic CO2 reduction constitute a significant advance in this area, where CH4 (12.03 mmol g−1 h−1) and C2H4 (3.55 mmol g−1 h−1) yields are achieved with a C2+ selectivity of 29.76% under concentrated natural sunlight. This work sets a new benchmark for EROI with an average solar‐to‐carbon‐fuel (STF) conversion efficiency greater than 0.045%. This work provides a strategy using the photo‐to‐thermal (PTT) conversion to enhance the photocatalytic CO2 reduction efficiency. Through the vulcanization, reactive sites are introduced between MXene layers and extended the near‐infrared response, which achieves an EROI efficiency greater than 0.045% under concentrated sunlight.