CO₂‐related solar to chemical conversions have gained extensive interest due to the great concerns on renewable energy utilization. Here, we have demonstrated a new synthetic route to C‐doped amorphous titanium oxide using a facile citric acid assisted sol‐gel method for efficient photocatalytic reduction of CO₂. The synthesized amorphous material exhibits a mesoporous structure with high specific surface area and a significantly narrowed band gap of 2.1 eV, which are crucial for solar light harvesting and adsorption/chemical activation of CO₂ for energy transformation. The amorphization, mesoporous structure, and the band structure of the C‐doped samples were also successfully tuned by controlling the annealing temperatures. The optimized catalyst annealed at 300 °C shows the highest specific surface area, favorable visible‐light response as well as the considerable performance for CO₂ photoreduction. Moreover, the further treatment of Al reduction can induce numerous surface oxygen vacancies on the amorphous sample and thus efficiently restrain the recombination of photogenerated carriers. Of significant importance is that the Al‐reduced catalyst achieves excellent performance with the space‐time yield of CH₄ and CO of 4.1 and 2.5 μmol g⁻¹ h⁻¹ for solar light, and 0.53 and 0.63 μmol g⁻¹ h⁻¹ for visible light, respectively. This sample is also stable for photocatalytic CO₂ transformation.

中文翻译：

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碳掺杂无定形氧化钛有效地光催化还原CO2

由于对可再生能源利用的高度关注，与CO ₂有关的从太阳能到化学的转换引起了广泛的兴趣。在这里，我们已经证明了一种使用简便的柠檬酸辅助溶胶凝胶法合成C掺杂无定形二氧化钛的新合成途径，可以有效地光催化还原CO ₂。合成的非晶态材料具有介孔结构，具有较高的比表面积和2.1 eV的明显变窄的带隙，这对于收集太阳光以及CO _2的吸附/化学活化至关重要用于能源转换。通过控制退火温度，还可以成功地调谐C掺杂样品的非晶化，中孔结构和能带结构。经过优化的，在300°C退火的催化剂显示出最高的比表面积，良好的可见光响应以及出色的CO _2光还原性能。而且，Al还原的进一步处理可以在无定形样品上引起许多表面氧空位，因此有效地抑制了光生载流子的重组。至关重要的是，Al还原催化剂具有出色的性能，CH ₄和CO的时空产率分别为4.1和2.5μmolg ^-1  h ^-1太阳光分别为0.53和0.63μmolg ^-1  h ^-1。该样品对于光催化CO ₂转化也是稳定的。