Photocatalytic reduction of CO₂ is considered as a promising strategy for production of a wide range of renewable hydrocarbon fuels by solar energy. In this investigation, a series of Ni and Bi doped TiO₂ catalysts with different Ni and Bi contents were synthesized by the conventional sol-gel method and tested for CO₂ photo-reduction under visible light irradiation. Synthesized nano-photo-catalysts were characterized by XRD, FESEM, TEM, DRS, PL, FTIR and BET analyses. BET results indicated that the doping of Ni or/and Bi in the TiO₂ framework resulted in BET specific surface area increment with respect to pure TiO₂. DRS analysis showed that Ni doped TiO₂, Bi doped TiO₂, and co-doped samples had narrower band gap energy and consequently considerably higher light absorption in the visible region compared with pure TiO₂. Doping Ni and Bi in TiO₂ suppressed the rate of electron-hole recombination as indicated by PL spectra. CO₂ adsorption capacity were increased in presence of Bi ions in comparison with pure TiO₂ and Ni doped sample as a result of reactant adsorption increase on the surface of catalyst. The yield of methane considerably increased in the presence of Ni and Bi doped samples. The highest methane production (21.13 μmol/g_cat) was obtained for 1 wt% Ni–3 wt% Bi co-doped TiO₂, which was almost 6.5 times greater than that for pure TiO₂.

光催化还原CO ₂被认为是通过太阳能生产各种可再生烃燃料的有前途的策略。在这项研究中，通过常规的溶胶-凝胶法合成了一系列具有不同Ni和Bi含量的Ni和Bi掺杂的TiO ₂催化剂，并在可见光照射下测试了CO _2的光还原性能。通过XRD，FESEM，TEM，DRS，PL，FTIR和BET分析对合成的纳米光催化剂进行了表征。BET结果表明，相对于纯TiO ₂，Ni或/和Bi在TiO ₂骨架中的掺杂导致BET比表面积增加。DRS分析表明，Ni掺杂的TiO 2，Bi掺杂的TiO ₂与纯TiO 2相比，共掺杂样品具有更窄的带隙能量，因此在可见光区域的光吸收明显更高。如PL光谱所示，在TiO _2中掺杂Ni和Bi抑制了电子-空穴复合的速率。与纯TiO ₂和Ni掺杂的样品相比，在Bi离子存在下，CO ₂吸附容量增加，这是由于反应物在催化剂表面上的吸附增加。在镍和铋掺杂样品的存在下，甲烷的产率显着提高。1％（重量）Ni-3％（重量）Bi共掺杂的TiO 2的甲烷产量最高（21.13μmol/ g _cat），几乎是纯TiO _2的6.5倍。