Death and Rebirth: Photocatalytic Hydrogen Production by a Self-Organizing Copper–Iron System

Abstract

This study provides detailed mechanistic insights into light-driven hydrogen production using an abundant copper–iron system. It focuses on the role of the heteroleptic copper photosensitizer [Cu(P∧P)(N∧N)]+, which can be oxidized or reduced after photoexcitation. By means of IR, EPR, and UV/vis spectroscopy as well as computational studies and spectroelectrochemistry, the possibility of both mechanisms was confirmed. UV/vis spectroscopy revealed the reorganization of the original heteroleptic photosensitizer during catalysis toward a homoleptic [Cu(N∧N)2]+ species. Operando FTIR spectroscopy showed the formation of a catalytic diiron intermediate, which resembles well-known hydrogenase active site models.