Photothermal-enabled metal-free polyfuran photocatalysts for efficient solar-to-hydrogen peroxide energy conversion from seawater

Solar-driven H2O2 photosynthesis from inexhaustible seawater is promising for alleviating increasingly-serious energy/environmental crises. Herein, a new metal-free photothermal-assisted photocatalyst containing strong π-stacked polyfuran D-A couples is synthesized by employing 5-hydroxymethylfurfural as precursor, which enables the highly-efficient H2O2 photosynthesis from seawater without any sacrificial agent. Its unique aromatic and quinoid furan alternating structure promotes the photogenerated charge transfer and the activation of oxygen molecules, thus remarkedly boosting H2O2 production rate. Furthermore, its localized photothermal and “electron bridge” effects can enhance the kinetic process of this reaction and accelerate the charge transfer, respectively, resulting in a high H2O2 yield of 1883.81 μmol g−1 h−1 with a high solar-to-chemical conversion efficiency of 0.48 % in seawater under simulated-sunlight irradiation. Impressively, it can achieve a high H2O2 concentration of 1867.81 μmol L−1 in natural seawater in one day under natural-sunlight irradiation, representing the first successful application of metal-free polyfuran photocatalysts for the photothermal-assisted H2O2 photosynthesis from natural seawater. [Display omitted] •Metal-free photocatalysts with π-stacked polyfuran couples are synthesized from HMF.•The unique aromatic and quinoid furan alternating structure can promote charge transfer.•Photothermal and electron bridge effect in HDPC can enhance the H2O2 generation kinetics.•HDPC can achieve a high H2O2 yield of 1867.81 μmol L−1 in one day under natural sunlight.