Nickel as a co-catalyst for photocatalytic hydrogen evolution on graphitic-carbon nitride (sg-CN): what is the nature of the active species?

The nature of a nickel-based co-catalyst deposited on a sol-gel prepared porous graphitic-carbon nitride (sg-CN), for photocatalytic H2 production from water, has been investigated. The formation of the active catalytic species, charge separation and recombination of the photogenerated electrons and holes during photochemical H2 evolution has been determined for the first time using in situ EPR spectroscopy.