Chemistry

Materials science

Water splitting

Optoelectronics

Composite number

Engineering

Composite material

Biochemistry

Carbon nitride

Heterojunction

Nanotechnology

Organic chemistry

Catalysis

Photocatalytic water splitting

Photocatalysis

Carbon fibers

Chemical engineering

Hydrogen

Nitride

Layer (electronics)

Doping

Nature Energy

Photocatalytic overall water splitting can be achieved using Z-scheme systems that mimic natural photosynthesis by combining dissimilar semiconductors in series. However, coupling well-suited H2- and O2-evolving components remains challenging. Here, we fabricate a Z-scheme system for photocatalytic overall water splitting based on boron-doped, nitrogen-deficient carbon nitride two-dimensional (2D) nanosheets. We prepare ultrathin carbon nitride nanosheets with varying levels of boron dopants and nitrogen defects, which leads to nanosheets that can act as either H2- or O2-evolving photocatalysts. Using an electrostatic self-assembly strategy, the nanosheets are coupled to obtain a 2D/2D polymeric heterostructure. Owing to their ultrathin nanostructures, strong interfacial interaction and staggered band alignment, a Z-scheme route for efficient charge-carrier separation and transfer is realized. The obtained heterostructure achieves stoichiometric H2 and O2 evolution in the presence of Pt and Co(OH)2 co-catalysts, and the solar-to-hydrogen efficiency reaches 1.16% under one-sun illumination. Splitting water using suspensions of particulate carbon nitride-based photocatalysts may be a cheap way to produce hydrogen, but efficiencies have remained low. Now, Shen and colleagues use doped carbon nitride-based Z-scheme heterostructures to split water with a solar-to-hydrogen efficiency of 1.1% in the presence of metal-based co-catalysts.

Boron-doped nitrogen-deficient carbon nitride-based Z-scheme heterostructures for photocatalytic overall water splitting