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Sequential pulsed laser ablation in liquid (PLAL) controlled the interfacial architec-ture of WO₃/g-C₃N₄ nanohybrids through two pre-optimized reciprocal routes. R1 formed WO₃@g-C₃N₄ by ablating g-C₃N₄ at 20 J cm⁻² in a preformed WO₃ colloid, whereas R2 formed g-C₃N₄@WO₃ by ablating WO₃ at 70 J cm⁻² in a preformed g-C₃N₄ colloid. These target-specific second-step fluences were established through prior work and preliminary optimization. XRD confirmed retention of monoclinic WO₃ in both hybrids. Relative to pristine WO₃, R1 reflections shifted 0.29–0.31° toward higher 2θ, compared with 0.14–0.15° for R2, while both retained a mean coherent-domain length of approximately 47 nm. Electron microscopy revealed WO₃ cores surrounded by carbon-nitride-rich shells in R1 and discrete WO₃-rich domains distributed over g-C₃N₄ sheets in R2. Their zeta potentials were −46.3 and −41.7 mV, respectively. AFM mean lateral feature sizes were 74.1 and 82.5 nm, respectively. Direct-transition Tauc analysis resolved energies of 1.80 and 3.04 eV for R1 and 1.80 and 2.95 eV for R2. R2 exhibited lower transmittance, whereas R1 delivered stronger photocatalysis. Under xenon-lamp irradiation, R1 achieved 83% methylene-blue degradation after 180 min with kₐₚₚ = 1.00 × 10⁻² min⁻¹, exceeding R2 at 71% and 7.03 × 10⁻³ min⁻¹. R1’s superior performance results from its continuous core–shell interface, carbon-nitride-rich adsorption surface, rougher topography, and stronger electrostatic attraction toward cationic dye molecules. These findings estab-lish ablation order and target-specific fluence as coupled controls of nanohybrid morphology, optical response, and photocatalytic performance.
