Tailoring oxygen evolution performances of carbon nitride systems fabricated by electrophoresis through Ag and Au plasma functionalization

The strategic interest in the production of green hydrogen by sunlight-activated water splitting has stimulated significant efforts aimed at the implementation of active and cost-effective catalysts for the oxygen evolution reaction (OER), the overall process bottleneck. Herein, we report on an original fabrication route to OER electrocatalysts based on graphitic carbon nitride. In particular, the target systems were deposited on conductive glass substrates via a simple electrophoretic technique and functionalized with highly dispersed noble metals (Au, Ag or Au + Ag) in low amounts by radio frequency (RF)-sputtering under mild conditions. An advanced material characterization revealed the possibility of tailoring carbon nitride morphology as a function of the used precursor and of achieving a homogeneous spatial distribution of the functionalizing metals. The latter ranged from atomically dispersed (silver), to low-sized nanoaggregates (gold) or partially alloyed core-shell nanoparticles (gold+silver), with an intimate metal-nitride interfacial contact. Functional tests evidenced a remarkable sensitivity to Vis light even at low applied potentials, and photoelectrocatalytic performances directly dependent on the nature of metal species and on the features of the underlying carbon nitride deposit. These evidences, rationalized mainly on the basis of Schottky junctions and the possible concurrence of surface plasmon resonance (SPR), candidate the proposed strategy as a versatile route to cheap and efficient OER electrocatalysts for energy conversion.