Recent advances in structural engineering of 2D hexagonal boron nitride electrocatalysts

Hexagonal boron nitride (h-BN) as a type of two-dimensional (2D) materials has gained significant attention in green energy applications recently. In the past, h-BN has mainly been regarded as inert materials because of the poor conductivity and is mainly used commercially as insulators. However, recent advances in materials science and nanotechnology have unveiled exciting applications of h-BN by taking advantage of the unique chemical and electrochemical properties, high thermal stability, as well as environmental friendliness. In the energy field, h-BN has not been researched as extensively as other 2D materials such as graphene and there have been few comprehensive reviews discussing the various aspects of the materials and applications. The objective of this review is to summarize recent results and applications of this unique class of materials and to provide guidance to future research and development of green energy systems based on h-BN. We first describe the physical and chemical modification strategies to convert insulating h-BN into the desirable conductive materials suitable for energy conversion. In addition to functionalization strategies, different synthetic methods and important properties of h-BN are reviewed. We then describe recent progress and applications of h-BN as electrocatalysts in energy applications, including the oxygen reduction reaction (ORR), hydrogen evolution reaction (HER), oxygen evolution reaction (OER), carbon dioxide reduction reaction (CO2RR), and nitrogen reduction reaction (NRR). The electrocatalytic mechanisms and impact on the materials performance are discussed and finally, the challenges and prospects for modified h-BN in the energy conversion field are discussed.