Enhanced Photocatalytic Degradation of Hazardous Formaldehyde over the Cu2O–TiO2 Based Binary-Photocatalysts at Ambient Temperature

Formaldehyde (HCHO), a prevalent indoor air pollutant released from furniture and building materials, poses significant health risks due to its carcinogenic nature. In this study, a binary cuprous oxide–titanium dioxide (Cu2O–TiO2) composite photocatalyst was synthesized via a hydrothermal method to enable efficient visible-light-driven degradation of gaseous formaldehyde at ambient temperature. The structural, morphological, and optical properties of the as-prepared catalysts were characterized using XRD, SEM, TEM, EDX, and UV-Vis spectroscopy. While pristine Cu2O exhibited a formaldehyde degradation efficiency of approximately 68% under white light illumination, the incorporation of TiO2 markedly enhanced the photocatalytic performance. Among the different mass ratios tested, the Cu2O–TiO2 (1:1) composite demonstrated the highest activity, achieving 83% degradation of formaldehyde within 240 min under white light. Enhanced performance is attributed to the formation of a heterojunction that reduces the effective bandgap, promotes charge separation, and suppresses electron–hole recombination. Additionally, the generation of carbon dioxide and water as end products confirmed complete mineralization. The catalyst also showed good reusability, retaining over 81% efficiency after five cycles. This work presents a cost-effective, stable, and visible-light-active Cu2O–TiO2 heterojunction photocatalyst with strong potential for indoor air purification applications.