Carbon, nitrogen and phosphorus containing metal-free photocatalysts for hydrogen production: progress and challenges

Abstract

Photocatalytic hydrogen production from water is a green and renewable path for solar fuel production. Hydrogen can be advantageously stored directly and burned without emission of deleterious CO and NO⨯ gases. Photocatalysis therefore shows significant promise as a part solution to a sustainable and affordable energy supply in an era post-fossil fuels. Influenced by the Fujishima–Honda effect, significant advances in photocatalytic hydrogen production have occurred at the laboratory-scale. For wide adoption however, the photocatalysts will need to be made from earth-abundant materials, be stable and scalable from laboratory-to-large-scale, and have high conversion efficiency. In this regard, metalfree photocatalysts show practical promise in meeting these requirements. To foster research in materials design, here we critically review recent significant developments in metal-free photocatalysts consisting of carbon, nitrogen and phosphorus, and discuss how future large-scale hydrogen production via overall water-splitting could be accomplished economically.