Recent advances of photocatalysts for nitrogen reduction reaction and mechanism behind them: How and why modifications change properties

Abstract

With the increasing demand for green production, the employment of pollution-free light in catalyzing ammonia production is receiving increasing attention. In order to achieve higher nitrogen fixation efficiency, many modification strategies including doping, anchoring, functionalization, defect engineering and heterostructure construction have been applied to enlarge the absorption range, facilitate the charge separation. However, in this process, the available type of atoms for doping and coupled substances for heterojunctions are almost obtained through a trial-and-error approach, consuming lots of time and resources. Fortunately, the above-mentioned issue can be significantly alleviated with the assistance of a clear mechanism, which can also provide guidance to select suitable modification measure for various systems, thereby promoting the emergence of more efficient photocatalysts. To this end, we classify and discuss the newly developed nitrogen fixation photocatalysts in recent years, and summarize the mechanism of improving nitrogen fixation efficiency by analyzing the changes in inherent electronic properties at the atomic level. First, we list the basic requirements and the corresponding difficulties of the photocatalytic nitrogen reduction. Second, several strategies, classified based on morphology and working mechanism, are investigated. Finally, the opportunities and future prospects are proposed on the basis of the conclusions we obtained.