Full solar spectrum responsive carbon nitride enabled by low‐temperature molten‐salt‐assisted magnesiothermic reduction

Abstract The solar energy conversion efficiency of graphitic carbon nitride (GCN)‐based photocatalysts is significantly hindered by the limited intrinsic absorption range and low carrier mobility of GCN. Herein, a novel carbon nitride (SC‐CN) with exquisitely designed electronic band structure is proposed by continual stoichiometric manipulation, introducing wide dispersed midgap states for stepwise electron excitation. Importantly, the modulation of electronic structure paves the way for multilevel electron transitions, resulting in the full solar spectrum absorption covering a range of 250–2500 nm. Moreover, these defect levels markedly enhance the nonradiative relaxation in SC‐CN, leading to a distinct photothermal effect where its temperature can be raised to 80°C under 100 mW cm −2 near‐infrared (NIR) light. Ultimately, a full solar conversion improvement for microcystin photoredox degradation is realized due to the synergetic interaction of photothermal effect and interfacial charge transfer in an SC‐CN@GCN heterojunction.