Photocatalytic CO₂ reduction to methanol is a promising method to solve the energy and environmental issues. Herein, copper species with different valences loading on TiO₂ via the oxidizing and reducing atmosphere treatment, denoted as Cu/Ti(air) and Cu/Ti(H₂), for CO₂ photoreduction. The methanol yield greatly increased on Cu/Ti(H₂) with low-valence copper species, which was 17-fold higher than that of Cu/Ti(air). It showed that the reducing atmosphere generated Ti³⁺ species and oxygen vacancies on Cu/Ti(H₂), leading to richer protons of surface hydroxyls adsorbed on surface and available photo-electrons. In addition, in-situ CO₂ adsorption-DRIFTS suggested that low-valence copper species of Cu/Ti(H₂) had better ability of CO₂ activation and CO*, HOCO⁻, HCOOH active intermediates adsorption, which further hydrogenated and conversed to CH₃OH, with the help of protons and photo-electrons. Therefore, owing to the synergistic effects of surface hydroxyl and low-valence copper species, Cu/Ti(H₂) was provided with the superior conversion and selectivity of CO₂ to methanol.

光催化CO ₂还原为甲醇是解决能源和环境问题的一种很有前景的方法。在此，不同价态的铜物质通过氧化和还原气氛处理负载在TiO ₂ 上，表示为Cu/Ti(空气)和Cu/Ti(H ₂ )，用于CO _{2 光}还原。Cu/Ti(H ₂ )与低价铜物种的甲醇产率大大增加，比Cu/Ti(空气)高17倍。结果表明，还原气氛在 Cu/Ti(H ₂ )上产生了 Ti ³⁺物种和氧空位，导致吸附在表面上的表面羟基质子和可用光电子更丰富。此外，现场CO ₂吸附-DRIFTS 表明Cu/Ti(H ₂ ) 的低价铜物种具有更好的CO ₂活化能力和CO*、HOCO ^-、HCOOH 活性中间体的吸附能力，可进一步加氢转化为CH ₃ OH，与质子和光电子的帮助。因此，由于表面羟基和低价铜物种的协同作用，Cu/Ti(H ₂ ) 具有优异的CO ₂转化为甲醇的转化率和选择性。