Visible-Light Driven H2O-to-H2O2 Reaction by Nitrogen-Enriched Resins for Photocatalytic Oxidation of an Organic Pollutant in Wastewater

A photocatalytic H₂O-to-H₂O₂ reaction for sustainable organic wastewater treatment is environmentally attractive. Phenolic resins, inexpensive metal-free photocatalysts, are capable of harvesting visible light. Herein, novel nitrogen-enriched resin photocatalysts with a desired band-gap energy (1.83-1.98 eV) for harvesting visible light were prepared by copolymerization of resorcinol and melem for simultaneous photocatalytic H₂O-to-H₂O₂ and oxidation of methylene blue. Under visible light irradiation for 5 h, very high yields of H₂O₂ (870-975 μM of H₂O₂/g/h) by RFM resin photocatalysts could be achieved. The photocatalytic H₂O₂ for reactive oxygen species (^•OH) and photogenerated h⁺ could account for high conversion (40% conversion under visible light irradiation within 3 h) in oxidation of methylene blue. Such unique low-cost metal-free resins demonstrate the visible light photocatalytic H₂O-to-H₂O₂ reaction which can synergize with the oxidation of organic pollutants in wastewater.

Looking for the “Dream Catalyst” for Hydrogen Peroxide Production from Hydrogen and Oxygen

The reaction between hydrogen and oxygen is in principle the simplest method to form hydrogen peroxide, but it is still a “dream process”, thus needing a “dream catalyst”. The aim of this review is to analyze critically the different heterogeneous catalysts used for the direct synthesis of H2O2 trying to determine the features that the ideal or “dream catalyst” should possess. This analysis will refer specifically to the following points: (i) the choice of the metal; (ii) the metal promoters used to improve the activity and/or the selectivity; (iii) the role of different supports and their acidic properties; (iv) the addition of halide promoters to inhibit undesired side reactions; (v) the addition of other promoters; (vi) the effects of particle morphology; and (vii) the effects of different synthetic methods on catalyst morphology and performance.