Porous hexagonal boron nitride sheets: effect of hydroxyl and secondary amino groups on photocatalytic hydrogen evolution

Hexagonal boron nitride (h-BN), an emerging two-dimensional material, has attracted great attention in various fields. However, due to its large band gap (ca. 6 eV), h-BN has not yet been exploited as a photocatalyst. Here, we demonstrate a porous h-BN sheets with rich hydroxyl (-OH) and secondary amino (-NH) groups, which can effectively decrease the band gap of h-BN. Porous h-BN sheets were synthesized via combustion of boron acid and urea at high temperature under nitrogen atmosphere. The as-obtained porous h-BN has a narrower band gap and a higher photocatalytic activity on hydrogen evolution than commercial h-BN. To further understand this photocatalytic performance, we investigated the groups, structure, and related optical and electrochemical properties for both porous and commercial h-BN. This work holds promise for h-BN to be used in the photocatalysis field.