Direct and efficient photocatalytic water splitting is critical for sustainable conversion and storage of renewable solar energy. Here, we propose a conceptual design of two-dimensional C3N4-based in-plane heterostructure to achieve fast spatial transfer of photoexcited electrons for realizing highly efficient and spontaneous overall water splitting. This unique plane heterostructural carbon ring (Cring)–C3N4 nanosheet can synchronously expedite electron–hole pair separation and promote photoelectron transport through the local in-plane π-conjugated electric field, synergistically elongating the photocarrier diffusion length and lifetime by 10 times relative to those achieved with pristine g-C3N4. As a result, the in-plane (Cring)–C3N4 heterostructure could efficiently split pure water under light irradiation with prominent H2 production rate up to 371 μmol g–1 h–1 and a notable quantum yield of 5% at 420 nm.

Fast Photoelectron Transfer in (Cring)–C3N4 Plane Heterostructural Nanosheets for Overall Water Splitting