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Mechanistic Insights into CO2 Reduction on Half-Metallic Oxygen-Vacant 2D-Janus TiCrCO2 MXene Surface
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DOI：10.1021/acsaem.6c01399.png)
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Abstract
En 中文
Artificial photosynthesis is a promising strategy to address environmental and energy challenges. However, its practical realization remains limited due to complex reaction pathways and insufficient molecular-level understanding. Recently developed 2D MXenes have emerged as attractive materials owing to their exceptional properties and have shown significant potential as catalysts and co-catalysts for CO2 reduction. In this work, we systematically investigate the photocatalytic efficiency of oxygen-vacancy-engineered two-dimensional (2D) TiCrCO2 Janus MXene (TiCrCO2(Ov)) for CO2 reduction employing spin-polarized density functional theory calculations. The TiCrCO2(Ov) system exhibits intrinsic half-metallicity, enabling spin-selective charge transport and efficient carrier separation. Hybrid HSE06 calculations reveal a suitable band gap (1.52 eV) and favorable band-edge alignment (CBM: −3.74 eV; VBM: −5.26 eV vs vacuum), providing sufficient driving force for both CO2 reduction and water oxidation. Strong optical absorption spanning the UV−visible region further supports its photocatalytic potential. Electronic structure analyses reveal strong Ti-d−CO2-p hybridization and stabilization of key intermediates through significant charge transfer. To understand the catalytic selectivity, both hydrogenation and de-oxygenation pathways were explored. Reaction pathway analysis demonstrates a favorable hydrogenation route toward HCOOH formation with a low energy barrier of 0.96 eV, identifying it as the dominant product. The high energy barrier for other reduction products like CO, HCHO, CH3OH, and CH4 indicates the selectivity of the selected catalysts towards HCOOH production. This study provides a mechanistic insight into the design of a catalyst for efficient and selective CO2 reduction, and the potential application of 2D Janus MXene materials further.
Keywords:
Hydrogenation
Inorganic carbon compounds
Oxides
Redox reactions
Two dimensional materials
photocatalytic CO2 reduction
Janus MXene
half-metallicity
density functional theory
oxygen vacancy engineering
formic acid selectivity
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4.5W
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