Electron‑Sponge S‑Scheme Heterojunctions via Mo–N Bridging Enable Highly Selective Photocatalytic CO 2 Methanation

Abstract

ABSTRACT The kinetic limitations of multi‐electron transfer present a fundamental challenge to achieve selective CO 2 photoreduction to CH 4 . This work pioneers an interface electron‐flux intensification strategy by constructing a Mo–N‐bridged S‐scheme phosphomolybdic acid (PMA)/carbon nitride (CN) heterojunction synergistically coupled with the electron‐sponge functionality of PMA, directing charge transfer and electron utilization pathways. PMA/CN‐2 materials exhibit remarkable CO 2 ‐to‐CH 4 conversion rate of 20.76 µmol·g −1 ·h −1 , representing a 148.3‑fold over CN (0.14 µmol·g −1 ·h −1 ), while the CH 4 selectivity sharply rises from 6.37% (CN) to 98.95% (PMA/CN‑2). X‐ray absorption fine structure (XAFS) and femtosecond transient absorption (fs‐TAS) spectroscopy reveal that N–Mo–O 5 coordination environment can regulate interfacial charge kinetics triggering ultrafast migration and consequent accumulation of photo‐induced electrons. Furthermore, in situ measurement, Gibbs’ energy changes and crystal orbital Hamilton populations (COHP) analysis elucidates the electronic modulation of Mo centers in Mo–N‐bridged PMA/CN heterojunction contributes to enhanced bonding with *CH 3 O at Mo–O 5 active sites for accelerating CH 4 generation. This manuscript establishes a foundational strategy for engineering atomically bridged S‐scheme heterojunctions with regulated electron dynamics, advancing the development of artificial photosynthesis systems for selective CO 2 ‐to‐fuel conversion.