2020 Roadmap on gas-involved photo- and electro- catalysis

In this roadmap, we address the development and perspectives of hydrogen evolution reaction, oxygen reduction reaction, oxygen evolution reaction, carbon dioxide reduction reaction and nitrogen reduction reaction through solar-, photoelectro- and electro-assisted ways. [Display omitted] Green reactions not only provide us chemical products without any pollution, but also offer us the viable technology to realize difficult tasks in normal conditions. Photo-, photoelectro-, and electrocatalytic reactions are indeed powerful tools to help us to embrace bright future. Especially, some gas-involved reactions are extremely useful to change our life environments from energy systems to liquid fuels and cost-effective products, such as H2 evolution (H2 production), O2 evolution/reduction, CO2 reduction, N2 reduction (or N2 fixation) reactions. We can provide fuel cells clean H2 for electric vehicles from H2 evolution reaction (HER), at the same time, we also need highly efficient O2 reduction reaction (ORR) in fuel cells for improving the reaction kinetics. Moreover, we can get the clean oxidant O2 from water through O2 evolution reaction (OER), and carry out some reactions without posing any pollution to reaction systems. Furthermore, we can translate the greenhouse gas CO2 into useful liquid fuels through CO2 reduction reaction (CRR). Last but not the least, we can get ammonia from N2 reduction reaction (NRR), which can decrease energy input compared to the traditional Hubble process. These reactions, such as HER, ORR, OER, CRR, and NRR could be realized through solar-, photoelectro- and electro-assisted ways. For them, the catalysts used play crucial roles in determining the efficiency and kinds of products, so we should consider the efficiency of catalysts. However, the cost, synthetic methods of catalysts should also be considered. Nowadays, significant progress has been achieved, however, many challenges still exist, reaction systems, catalysts underlying mechanisms, and so on. As extremely active fields, we should pay attention to them. Under the background, it has motivated us to contribute with a roadmap on ‘Gas-Involved Photo- and Electro-Catalysis’.