Graphitic carbon nitride (g-C3N4) being a non-metallic oxygen reduction reaction (ORR) photocatalyst has attracted much attention in the generation of H2O2. Nevertheless, the weak O2 adsorption capacity and inefficient separation of charge carriers greatly restrict the production efficiency of H2O2. Herein, iodine ions were used as invisible chemical scissors to tailor the tubular g-C3N4 (TCN) precursor, and relatively ultrathin g-C3N4 nanosheets were prepared (TCN/NaI). The obtained TCN/NaI exhibits alkali metal (Na+) and hydroxyl (–OH) co-modification, and shows the highest H2O2 generation rate (1935.61 μM h−1), greatly exceeding that of bulk g-C3N4 (BCN, 31.96 μM h−1) and TCN (129.32 μM h−1). In addition, excited states calculations of BCN + O2 and TCN/NaI + O2 further reveal that the electron of the β spin–orbital in TCN/NaI can transfer to the π* orbital of O2 more easily than that in BCN, thus enhancing the activation of O2. This work not only provides in-depth insights into the photocatalytic ORR for the H2O2 production mechanism, but also shows that the synergy of structure modification and doping can be further expanded to other semiconductors for photocatalytic applications.
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