Multifunctional diamond-based catalysts: Promising candidates for energy conversions in extreme environments—A mini-review

In order to properly utilize the abundant CO₂ and water resources, various catalytic materials have been developed to convert them into valuable chemicals as renewable fuels electrochemically or photochemically. Currently, most studies are conducted under mild laboratory conditions, but for some extreme environments, such as Mars and space stations, there is an urgent need to develop new catalysts satisfying such special requirements. Conventional catalytic materials mainly focus on metals and narrow bandgap semiconductor materials, while the research on wide and ultrawide bandgap materials that can inherently withstand extreme conditions has not received enough attention. Given the robust stability and excellent physico-chemical properties of diamond, it can be expected to perform in harsh environments for electrocatalysis or photocatalysis that has not been investigated thoroughly. Here, this review summarizes the catalytic functionality of diamond-based electrodes with various but tunable product selectivity to obtain the varied C₁ or C₂₊ products, and discusses some important factors playing a key role in manipulating the catalytic activity. Moreover, the unique solvation electron effect of diamond gives it a significant advantage in photocatalytic conversions which is also summarized in this mini-review. In the end, prospects are made for the application of diamond-based catalysts under various extreme conditions. The challenges that may be faced in practical applications are also summarized and future breakthrough directions are proposed at the end.