Multiscale modifications of carbon nitride to strengthen reaction kinetics and lower thermodynamic barriers for efficient photocatalytic oxygen evolution

Photocatalytic oxygen evolution reaction (OER) is pivotal for sustainable energy systems yet lacks high-performance catalysts capable of strong visible light absorption, robust charge dynamics, fast reaction kinetics, and high oxidation capability. Herein, we report the multiscale optimization of carbon nitride through the construction of porous curled carbon nitride nanosheets (CNA-B30) incorporating boron center/cyano group Lewis acid-base pairs (LABPs). The unique chemical and structural features of CNA-B30 extended the photoabsorption edges of π → π* and n → π* electronic transitions to 470 nm and 715 nm, respectively. Planar distortion and LABPs induced charge redistribution, enhancing the built-in electric field to promote efficient charge dissociation and transport. Moreover, boron atoms elevated the valence band of carbon nitride and served as active oxidation sites, effectively lowering the thermodynamic barrier for water oxidation. As a result, CNA-B30 demonstrated outstanding OER activity, achieving 586.5μmol g^-1 h^-1 (λ > 420 nm) without co-catalysts. With the addition of a Co co-catalyst, the oxygen evolution rate increased to 2085.5 μmol g^-1 h^-1 (λ > 420 nm), and an apparent quantum efficiency of 5.8 % at 420 nm, surpassing most state-of-the-art OER photocatalysts. This work offers valuable insights into designing advanced OER photocatalysts for efficient solar fuel production.