Modulating the Charge‐Transfer Step of a p–n Heterojunction with Nitrogen‐Doped Carbon: A Promising Strategy To Improve Photocatalytic Performance

Engineering p–n heterojunctions among metal oxide semiconductors to provide a built‐in electric field is an efficient strategy to facilitate the separation of photogenerated electrons and holes and improve their photocatalytic activities. However, the inherent poor conductivity of p–n heterojunctions still limits the charge‐transfer step and thus hampers their practical application in photocatalysis. In this work, a nitrogen‐doped carbon‐coated NiO/TiO2 p–n (NCNT) heterojunction with hierarchical mesoporous sphere morphology was synthesized by in situ pyrolytic decomposition of nickel–titanium complexes. The NiO/TiO2 p–n heterojunction in NCNT was fully characterized by several techniques, supported by theoretical calculations and Mott–Schottky plots. On coating with a thin nitrogen‐doped carbon layer, the electron transfer of the obtained p–n heterojunction could be significantly enhanced. On account of the favorable structural features of the p–n heterojunction with nitrogen‐doped carbon coating and hierarchical mesoporous structure, NCNT exhibited excellent photocatalytic activity toward various reaction systems, including the hydrogen evolution reaction and the visible‐light‐induced hydroxylation of phenylboronic acids.