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.