Photo-induced redox catalysis for proton reduction to hydrogen with homogeneous molecular systems using rhodium-based catalysts

•Molecular multi-component photocatalytic systems toward H2 production using rhodium catalysts are reviewed.•Ruthenium and iridium complexes have been used as photosensitizers in these photocatalytic systems in association with a sacrificial electron donor.•Assembled molecular structures in which the catalyst and the photosensitizer are covalently linked are also presented.•Systems functioning in pure aqueous solution are specially highlighted and some of them have proved particularly efficient.•Mechanistic aspects of photochemical H2 evolution catalyzed by these multi-component systems will be also discussed in detail.