Converting CO₂ into chemicals is a promising avenue to mitigate the energy crisis and global warming. Herein, two-dimensional (2D) heterojunctions of TiO₂/Ti₃CN MXene were fabricated through a facile hydrothermal oxidation method and used as the photocathode in photoelectrocatalytic (PEC) CO₂ reduction. The in situ grown TiO₂/Ti₃CN heterojunctions demonstrate excellent light absorption abilities, possess large specific surface areas and Ti³⁺ species, which are beneficial to the generation and transportation of photoelectron-hole pairs. In a new PEC system of Pd@TiO₂/Ti₃CN||SCE||BiVO₄, formate, methanol and C₂ of ethanol were obtained as the major reduction products, with the maximum and total formation rate of 45.6 μM cm⁻²h⁻¹. Furthermore, density functional theory (DFT) calculations indicate that TiO₂/Ti₃CN heterojunction can spontaneously activate CO₂ and stabilize the key reaction intermediates for facilitating HCOOH production. This research highlights the great prospect of titanium carbonitrides MXene in the green energy conversion field.

将 CO ₂转化为化学品是缓解能源危机和全球变暖的有希望的途径。_{在此，通过简便的水热氧化方法制备了 TiO 2} /Ti ₃ CN MXene的二维 (2D) 异质结，并将其用作光电催化 (PEC) CO ₂还原的光电阴极。原位生长的TiO ₂ /Ti ₃ CN异质结表现出优异的光吸收能力，具有较大的比表面积和Ti ³⁺种类，有利于光电子-空穴对的产生和传输。在 Pd@TiO ₂ /Ti ₃ CN||SCE||BiVO _{4的新 PEC 系统中}、甲酸盐、甲醇和乙醇的C ₂作为主要还原产物，最大和总生成率为45.6 μM cm ^-2 h ^-1。此外，密度泛函理论 (DFT) 计算表明，TiO ₂ /Ti ₃ CN 异质结可以自发激活 CO ₂并稳定关键反应中间体，从而促进 HCOOH 的生产。该研究凸显了钛碳氮化物MXene在绿色能源转换领域的巨大前景。