Figure . a) Commonly presented putative mechanism for nickel/photoredox dual catalyst systems. Many variants of this mechanism are possible, due to the large number of photoactive species present that can initiate reactions with different substrates. It is reasonable to hypothesize that multiple mechanisms may be operational simultaneously, and the dominant mechanism is likely to be substrate and reaction specific, and dependent on the relative rates and the nature and concentration of the species present. b) This work: utilising mechanochemistry to develop solvent-minimized metallaphotoredox catalysis reactions.