Construction of a new ternary α-MoO3–WO3/CdS solar nanophotocatalyst towards clean water and hydrogen production from artificial wastewater using optimal design methodology

Abstract

Photocatalytic wastewater remediation and hydrogen generation were successfully achieved using a novel α-MoO_3(0.03)–WO_3(0.36)/CdS_(0.61) heterojunction photocatalyst, fabricated by a solid-state approach. Through statistical optimal design of experiments (ODOE), simplex centroid design (SCD) and Box–Behnken design (BBD) were used to optimize the preparation and photocatalytic processes. The effects of combinatorial catalyst ratios on the photocatalytic responses were modeled using SCD under ultraviolet and visible light factors. Using BBD, the photodegradation experiments were fitted to the quadratic polynomial relationship with significance terms in the order of pH > catalyst dose > pollutants concentrations. The apparent first-order rate constants (K_app) of the developed ternary photocatalyst revealed that the solar-driven photoreaction is 1.4 times higher than the visible activation. The photocatalytic activities reached a maximum of 75% removal of total organic contaminants (TOC) and hydrogen yield of 8 μmol g⁻¹ h⁻¹ after 6 h of solar-harvesting with good photostability and durability for 5 cycles. The notable oxidation–reduction photoreaction of the ternary photocatalyst is attributed to the constructed Z-scheme by the synergic CdS–WO₃–α-MoO₃ heterojunction interaction. This work proves the power of ODOE to manufacture a photostable α-MoO_3(0.03)–WO_3(0.36)/CdS_(0.61) solar-photocatalyst for a green environment.