Noble metal free hydrogen evolution catalysts for water splitting.
Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource derived electricity and direct solar to hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal free hydrogen evolution catalysts to make the water splitting process more energy efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER) We review several important kinds of heterogeneous non precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition catalytic activity relationship. We also summarize some important examples showing that non Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar to hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts.
Chemical Society reviews