Interfacially orchestrated S-scheme photoactive microreactor: Ag2WO4@CuWO4@rGO composite for coupled photocatalytic degradation and energy storage

Designing a single heterostructured material that can coordinate charge generation, separation, and utilization across environmental and energy applications remains a key challenge in photocatalysis and electrochemical engineering. Here, a hierarchically integrated Ag 2 WO 4 @CuWO 4 @rGO (AgCuW-rGO) composite is presented as a conductive-layer S-scheme heterostructure that couples visible-light pollutant degradation with battery-type energy storage within one platform. The Ag 2 WO 4 domain provides light-induced electron enrichment, while CuWO 4 acts as a hole-transfer mediator, and the rGO outer layer functions as a continuous electron highway and mechanical buffer. Together, these components establish an internal electric field and promote S-scheme-like charge migration, as supported by photoluminescence quenching, reduced charge-transfer resistance from electrochemical impedance spectroscopy, Mott-Schottky analysis, and IMVS/IMPS carrier-lifetime measurements. Nyquist analysis indicates that the interfacial charge-transfer resistance (R ct ) is reduced by approximately a factor of 2 compared with the single oxides (10² Ω scale), consistent with longer carrier lifetimes and stable transient photocurrent. Under visible-light irradiation, 96% of pramipexole is removed within 35 min (k = 0.1069 min⁻¹, AQY = 0.325%), driven by spatially separated redox sites whose band-edge positions are thermodynamically compatible with O 2 / • O 2 − (-0.33 V) and O H − / • O H (+1.99 V at pH 7), enabling the generation of complementary •O₂⁻ and •OH radicals. When deployed as an electrode, the same interface delivers high-rate, reversible charge storage with a specific capacity of 1092.7 mAh g⁻¹ at 0.1 C, low polarization, and Coulombic efficiency above 95% over 100 cycles. This dual-functional microreactor illustrates a generalizable design strategy in which plasmon-assisted excitation, semiconductor coupling, and rGO conduction cooperatively regulate charge flow for both photo-oxidative catalysis and electrochemical energy conversion.