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

Abstract 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%.