Novel matcha green tea extract for green sol-gel synthesis of TiO2: enhancement of surface morphology to improve photocatalytic performance

A commercial TiO2 heterogeneous photocatalyst, Degussa, p-25, is successfully applied under artificial UV irradiation for oxidation of organic pollutants. However, it suffers from limited surface area, thus affecting its photocatalytic performance and restricting its feasibility for industrial applications. The current research aimed to address this limitation and therefore it investigated, for the first time, matcha green tea (MGT) as novel extracted material to synthesise green TiO2 photocatalyst from three weighted powders of first harvest (GF1, GF2, GF3) and second harvest (GS1, GS2, GS3) using sol-gel method (an effective method in controlling surface morphology). To achieve this aim, a working protocol was adopted in three stages (chemical and green synthesis of TiO2, characterisation of synthesised photocatalysts using relevant analytical techniques and evaluation of their photocatalytic performance with methylene blue using batch photoreactor). Experimentally, surface morphology of green TiO2 photocatalysts in terms of crystallite sizes, mean particle size, surface roughness and BET surface area (SBET) as found by analyses of EDX, FE-SEM, AFM and BET, respectively was significantly enhanced when compared with chemically control TiO2 (CP). The best characterisation results of green TiO2 photocatalysts were at GF2 and GS2. In particular, the SBET results for GF2 and GS2 were 164.44 and 217.66 m2/g, respectively compared with CP (13.78 m2/g). Photocatalytic degradation of MB for GF2 and GS2 was 90 and 98%, respectively. Photocatalytic mineralisation of MB was 88% for GF2 and 97% for GS2. In conclusion, MGT could significantly modify surface morphology of TiO2 photocatalyst towards enhancing its photocatalytic performance.