Catalytic effects of molybdate and chromate–molybdate films deposited on platinum for efficient hydrogen evolution

BACKGROUND Sodium chlorate (NaClO3) is extensively used in the paper industry, but its production uses strictly regulated highly toxic Na2Cr2O7 to reach high hydrogen evolution reaction (HER) Faradaic efficiencies. It therefore important find alternatives either replace or reduce concentration. RESULTS The concentration can be significantly reduced by using Na2MoO4 as an electrolyte co-additive. millimolar range shifts platinum cathode potential less negative values due activating effect of cathodically deposited Mo species. also acts a stabilizer electrodeposited chromium hydroxide has minor on HER efficiency. X-ray photoelectron spectroscopy (XPS) results show cathodic deposition molybdenum different oxidation states, depending conditions. Once was present, not detected XPS, it likely that only trace levels were deposited. Using electrochemical measurements and mass spectrometry we quantitatively monitored H2 O2 rates. indicate 3 μmol L−1 (contrary current industrial 10–30 mmol L−1) sufficient enhance efficiency 15%, co-adding 10 activated while avoiding detrimental generation from chemical reactions. Higher concentrations led increased oxygen production. CONCLUSION Careful tuning molybdate performance process chromate micromolar range. These insights could exploited efficient photocatalytic water splitting remediation wastewater. © 2023 Authors. Journal Chemical Technology Biotechnology published John Wiley & Sons Ltd behalf Society Industry (SCI).