Bi2MoO6/Bi2MoO6–x S-Scheme Homojunction for Efficient Photocatalytic N2 Reduction

Ammonia is in high demand and widely used, yet its production still predominantly relies on the energy-intensive Haber–Bosch process, highlighting the urgent need for a milder alternative technology. Photocatalytic N2 fixation shows great promise in this regard despite the challenge of developing high-efficiency catalysts. In this study, we successfully prepared micronano spherical Bi2MoO6/Bi2MoO6–x S-Scheme homojunctions using a simple solvothermal-calcination coupling method, which offer unique advantages for nitrogen fixation catalysis: (i) the micronano structure mitigates the agglomeration issue common in nanomaterials, thereby exposing more active sites; (ii) the in situ constructed S-Scheme homojunction features a high-quality surface and interface structure, enhancing the spatial separation and transport of photogenerated charges and preserving strong redox capabilities; and (iii) the oxygen-rich vacancy structure promotes the N2 adsorption and activation. Thanks to those favorable properties, the Bi2MoO6/Bi2MoO6–x (BMO/BMOOV) S-Scheme homojunction demonstrates exceptional ammonia production efficiency, with a NH4+ generation rate of 238.7 μmol g–1 h–1 under simulated sunlight, which is over 5.2 times higher than that of pristine Bi2MoO6 (BMO) and significantly outperforms other reported similar catalytic systems (see Table S1). This work introduces a simple and versatile method for synthesizing homojunctions, potentially inspiring the development of more efficient photocatalysts for nitrogen fixation and beyond.