The photocatalytic activity of NiO/Ni nanoparticles (NPs) supported on defective graphene (NiO/Ni-G) has been tested for the photoassisted CO₂ reduction with H₂. NiO/Ni-G was prepared by H₂ reduction of NiCl₂ adsorbed on few-layers defective G and storage under air. An optimal Ni loading of 23 wt% was found, reaching the maximum specific CH₄ formation rate (642 μmol CH₄ g_Ni⁻¹ h⁻¹ at 200 °C) and quantum yield of 1.98%. Under the same conditions Ni NPs supported on silica-alumina or NiO NPs exhibit notably lower specific CH₄ production rates than NiO/Ni-G. It was found that H₂O formed in the reaction has a detrimental influence on the photocatalytic activity and evidence supports that H₂O desorption is one of the reasons why the system requires heating. Under continuous flow operation, undesirable water molecules were easier desorbed from the NiO/Ni-G photocatalyst than in the batch mode, reaching a steady specific CH₄ production rate of 244.8 μL h⁻¹ for 50 mg of NiO/Ni-G catalyst with a residence time of 3.1 s. Quenching experiments with electron donor of different oxidation potential (dimethylaniline, anisole and p-xylene) are compatible with a mechanism involving photoinduced charge separation.

测试了负载在有缺陷的石墨烯上的NiO / Ni纳米颗粒（NPs）的光催化活性（NiO / Ni-G）对H ₂进行的光辅助CO ₂还原。通过H ₂还原吸附在几层缺陷G上的NiCl ₂并在空气中存储来制备NiO / Ni-G 。发现最佳的Ni负载量为23wt％，达到最大的比CH ₄形成速率（200℃下642μmolCH ₄  g _Ni ^-1  h ^-1）和量子产率为1.98％。在相同条件下，负载在二氧化硅-氧化铝上的Ni NP或NiO NP的CH ₄生成速率明显低于NiO / Ni-G。发现H ₂反应中形成的O对光催化活性有不利影响，证据支持H ₂ O的解吸是系统需要加热的原因之一。在连续流动操作下，与分批模式相比，不良的水分子更容易从NiO / Ni-G光催化剂中解吸，对于50 mg NiO / Ni-G催化剂，稳定的CH ₄特定比CH ₄生产率为244.8μLh ^-1。停留时间为3.1 s。用具有不同氧化电位的电子给体（二甲基苯胺，苯甲醚和对二甲苯）进行的猝灭实验与涉及光致电荷分离的机理兼容。