Generation of holes from intra-valence band for enhanced oxidation potentials under visible light

Abstract

Breaking the trade-off between oxidation potential and spectral response range has been an enduring challenge in the field of photocatalysis. Here, we present a general approach to initiating intra-valence band (intra-VB) hole generation in organic conjugated molecular crystals under visible light irradiation. The electron-deficient precursor with the intrinsically empty side-VB is introduced by Fe3+, enabling electron transition from the intra-VB to the side-VB. By studying five typical conjugated photocatalysts, we demonstrate that holes with strong oxidation potentials (up to 3.85 V vs. RHE) are generated under visible light. For PTCDA molecular crystals, the holes from the intra-VB (HOCO-1 β) couple with carbonyl groups, forming hole-coupled carbonyl sites (–C=O+) and extending the hole lifetime by 241 times to 84.5 ns. Efficient hole transfer from –C=O+ to reactants subsequently initiates oxidation reactions. The high-energy photogenerated holes exhibit scalable oxidation applicability, such as the degradation of organic pollutants in water under natural sunlight.