Nanodiamond: a promising metal-free nanoscale material in photocatalysis and electrocatalysis

Benefiting from its surface-rich functional groups, eco-friendliness, impressive electrochemical properties, excellent light absorption, structural tunability at the atomic/morphological level, and ultra-high stability under harsh conditions, nanodiamond has emerged as a promising carbon-based non-metallic material in the field of energy conversion such as electrocatalysis and photocatalysis. Furthermore, nanodiamond, as a new generation of green catalysts, can overcome the poisoning of catalysts by complex pollutants in advanced oxidation processes, thus effectively removing organic matter from water, which is unparalleled in reducing the cost of water purification and avoiding secondary cross-contamination of water by traditional heavy metal-based catalysts. Here, we review the research and development of nanodiamonds as major electrocatalysts and photocatalysts for energy conversion and for air/water treatment for environmental remediation. The relevant properties, trimming strategy, mechanistic understanding, and design principles of nanodiamond as a catalyst are described, as well as the challenges and prospects of this emerging field.