Interaction of metal ions in high efficiency seawater hydrogen peroxide production by a carbon-based photocatalyst

Photocatalytic seawater splitting is a promising method for producing hydrogen peroxide (H2O2). However, the presence of metal ions usually deactivates catalysts and causes undesirable reactions, highlighting the need for deeply understanding these interactions. Herein, a carbon-based composite photocatalyst (CQM) is fabricated for photocatalytic production of H2O2. The metal ions strongly affect the photocatalytic activity of the CQM catalyst with order of Mg2+ > Al3+ > Ca2+ > K+, consistent with the surface effective electron concentration calculated from transient photovoltage (TPV) technology. Notably, with the presence of Mg2+ at 0.36 mol L-1, the H2O2 yield is 12,812 mu mol g(-1) h(-1). Under the guidance of machine learning, the H2O2 yield is further improved to 19,560 mu mol g(-1) h(-1) by adjusting the concentration of multiple ions. Significantly, in a real seawater system, the photoproduction of H2O2 on CQM reaches up to a recorded value of 11306 mu mol g(-1) h(-1) under visible light illumination.

Automated summary

Photocatalytic seawater splitting is a promising method for producing hydrogen peroxide. The presence of metal ions strongly affects the photocatalytic activity of a carbon-based composite photocatalyst, with magnesium ions having the highest impact. By adjusting the concentration of multiple ions, the yield of hydrogen peroxide is significantly improved. This research achieved remarkable results in a real seawater system.