Synergistic hybridization of twin-induced red/black phosphorus and tungsten oxide as homo-hetero dynamic dual junctions for Z-scheme CO₂ photoreduction

Resembling a distinctive stratum of chemical transformations, photocatalysis employs the energy from the Sun to drive thermodynamically uphill reactions by simply emulating what nature does best photosynthesis; photocatalysis therefore promises a sustainable solution to circumvent the increasingly tense environmental threats and energy crisis. In this contribution, we shed light on the opportune design and development of a dual Z-scheme photocatalytic system with homo-hetero junctions using mixed-phase red/black phosphorus (RP/BP) and tungsten oxide (WO3) in regulating charge steering for directional electron-hole transfer to drive efficient CO2 reduction. Fascinatingly, the ternary composite material (RP/BP@WO3) displayed a striking enhancement in optical absorption capacity, which extended from the ultraviolet up to the near-infrared region, rendering its capability of maximizing photon absorption to power efficacious photocatalytic reactions. With the endowment of two effective charge transport pathways that feature a cascade electron flow profile, the RP/BP@WO3 dual Z-scheme photocatalyst achieved a CH4 yield of 6.21 μmol g-1 over 6 h under visible light illumination, whereas the pristine counterparts, namely, RP, WO3, and RP/BP, did not produce any CH4 yield. The amalgamation of RP/BP homojunction as the reduction catalyst and WO3 as the oxidation catalyst intriguingly serve as a complement to provoke CO2 reduction to CH4. The phenomenon is explicated by the formation of an arrow-up dual Z-scheme system that is governed by an internal electric field from the homo-hetero junctions which bestows strong redox potentials and favors the separation and transfer of photoinduced charge carriers, leading to increased participation of electron-hole pairs in redox reactions for improved photoconversion performance.