To address the over-emission of CO₂, the construction of new heterojunction materials is a promising approach for the photoelectrocatalytic (PEC) conversion of CO₂ into valuable chemicals. Herein, a series of heterojunctions of TiO₂/TiN nanotube arrays were designed and fabricated by anodic oxidation of titanium plates, followed by in situ partial oxidation to form heterojunctions. The surface of the heterojunction with nitrogen instead of oxygen contained more active Ti³⁺ species, and the oxygen vacancies were able to harvest solar light and showed excellent performance in the PEC reduction of CO₂. As a porous material, the TiO₂/TiN nanotube supports good adsorption of CO₂ as well as a confined space favoring C–C coupling. Operando Fourier transform infrared (FTIR) analysis revealed that the active species *COOH? and *CHO were the major intermediates. Density functional theory (DFT) calculations revealed that the highly active hydrogen atoms could attach to the surface of the heterojunction to form Ti–H species with Ti³⁺, and the existence of nitrogen atoms could promote the migration of lattice oxygen to form new oxygen vacancies, which is conducive to the adsorption and coupling of CO₂ and intermediates. The vibration frequency of Ti–H predicted by DFT calculations matches well with the operando FTIR observations. The PEC cell of Pd/R-TiO₂/TiN-30|SCE|BiVO₄ efficiently produced carbon-based chemicals at a rate of 115.9 μmol L⁻¹ h⁻¹ cm⁻² with high selectivity for C₂ products. The total efficiency of the PEC cell approached 6.0%, exceeding that of the plant cell by 0.4%. Isotopic labeling experiments of ¹³CO₂ and H₂¹⁸O verified the elemental source and inferred the reaction pathway via highly active hydrogen.

_{为了解决CO 2}的过度排放问题，构建新型异质结材料是将CO ₂光电催化(PEC) 转化为有价值化学品的一种很有前途的方法。在此，通过对钛板进行阳极氧化，然后原位部分氧化形成异质结，设计并制备了一系列TiO _{2 /TiN纳米管阵列异质结。}氮取代氧的异质结表面含有更多的活性Ti ³⁺物种，氧空位能够收集太阳光，在CO ₂的PEC还原中表现出优异的性能。作为多孔材料，TiO ₂ /TiN纳米管支持良好的CO吸附₂以及有利于 C-C 耦合的密闭空间。Operando Fourier 变换红外 (FTIR) 分析表明活性物质 *COOH? *CHO 是主要的中间体。^{密度泛函理论（DFT）计算表明，高活性氢原子可以附着在异质结表面与Ti 3+}形成Ti-H物种，氮原子的存在可以促进晶格氧的迁移形成新的氧空位，有利于CO ₂及其中间体的吸附偶联。DFT 计算预测的 Ti-H 的振动频率与原位 FTIR 观测结果非常吻合。_{Pd/R-TiO 2} /TiN-30|SCE|BiVO ₄的PEC电池^{以 115.9 μmol L −1} h ⁻¹ cm ⁻²的速率高效生产碳基化学品，对 C ₂产品具有高选择性。PEC电池总效率接近6.0%，超过植物电池0.4%。¹³ CO ₂和H ₂ ¹⁸ O的同位素标记实验验证了元素来源并推断了通过高活性氢的反应途径。