Photocatalytic hydrogen peroxide splitting on metal-free powders assisted by phosphoric acid as a stabilizer

Hydrogen peroxide (H(2)O(2)) has received increasing attention as an energy carrier. To achieve a sustainable energy society, photocatalytic H(2)O(2) splitting (H(2)O(2) (l) → H(2) (g)( + )O(2) (g); ΔG° = + 131 kJ mol(−1)) is a desirable reaction for on-site H(2) generation. However, this reaction has not been reported because conventional photocatalysis decomposes H(2)O(2) by disproportionation (H(2)O(2) (l) → H(2)O (l) + 1/2O(2) (g); ΔG° = −117 kJ mol(−1)) and by promoting H(2)O(2) reduction instead of H(+) reduction. Here we report the successful example of H(2)O(2) splitting. Visible light irradiation of a graphitic carbon nitride loaded with graphene quantum dots as co-catalysts (GQDs/g-C(3)N(4)) in a H(2)O(2) solution containing phosphoric acid (H(3)PO(4)) produces H(2). H(3)PO(4) associates with H(2)O(2) via hydrogen bonding, and this stabilization of H(2)O(2) suppresses its reduction, thus promoting H(+) reduction. The all-organic photosystem with H(3)PO(4) as a stabilizer may provide a basis of photocatalytic H(2)O(2) splitting.