Effects of halogen ligands of complexes supported by bis(methylthioether)pyridine on catalytic activities for electrochemical and photochemical driven hydrogen evolution

Reactions of bis(methylthioether)pyridine (btep) with CuX2 (X = Br and Cl) form two new complexes, [Cu(btep)Br2] and [Cu(btep)Cl2], respectively, which have been determined by X‐ray crystallography. Both of them can serve as catalysts for electrochemical and photochemical driven hydrogen evolution. Under an overpotential (OP) of 837.6 mV, [Cu(btep)Br2] or [Cu(btep)Cl2] can electrocatalyze hydrogen evolution from a neutral water with a turnover frequency (TOF) of 373 and 120 mol of hydrogen per mole of catalyst per hour (mol H2/mol catalyst/h), respectively. Under blue light, mixing with CdS nanorods (CdS NRs) as a photosensitizer, and ascorbic acid (H2A) as a sacrificial electron donor, the photolysis of an aqueous solution (pH 4.5) with [Cu(btep)Br2] or [Cu(btep)Cl2] can provide 6180 and 5120 mol of H2 per mole of catalyst (mol of H2 (mol of cat)−1) during 48‐h irradiation with an average apparent quantum yield of 16.7% and 11.0%, respectively. The results show that [Cu(btep)Br2] shows a more efficient activity for H2 generation than [Cu(btep)Cl2]. Several electrochemical and photochemical measurements and analysis are carried out to study catalytic mechanism for H2 production. The reaction of bis(methylthioether)pyridine (btep) with CuX2 (X = Br and Cl) form two complexes, [Cu(btep)Br2] and [Cu(btep)Cl2], respectively. Both of them can act as catalysts for hydrogen evolution. [Cu(btep)Br2] shows a more efficient activity for H2 generation than [Cu(btep)Cl2].