Sol–gel synthesis of ZnO @ SiC heterojunctions from photovoltaic waste for enhanced paracetamol photodegradation

Abstract

Abstract Exponential growth in photovoltaic energy production has created a critical environmental challenge: managing silicon carbide (SiC) waste from wafer cutting processes. This study addresses this challenge by transforming photovoltaic waste into high‐value photocatalytic materials. Zinc oxide@silicon carbide (ZnO@SiC) heterojunction photocatalysts with varying SiC mass ratios (1, 3, and 7 wt%) were successfully synthesized via a sol–gel route. Comprehensive characterization confirmed the hexagonal wurtzite structure of ZnO and the formation of a heterojunction with type‐II band alignment characteristics. The ZnO@SiC‐3% composite exhibited exceptional photocatalytic performance, achieving complete degradation of paracetamol (PCT) (20 mg.L −1 , pH = 7.5) after 180 min under UV irradiation (365 nm). This improvement is attributed to enhanced charge separation and interfacial electron transfer at the ZnO@SiC interface, supported by band gap narrowing from 3.12 to 3.04–3.08 eV. Radical scavenging experiments confirmed the dominant role of •O 2 − and •OH in PCT degradation. Kinetic studies followed a pseudo‐first‐order model, with ZnO@SiC‐3% exhibiting a rate constant of 0.0256 min −1 , which is approximately twofold higher than that of pure ZnO (0.0128 min −1 ). The optimal catalyst dosage was 750 mg.L −1 . Efficient degradation was maintained across a broad pH range (2.5–7.5). The catalyst retained 85% of its initial activity after four cycles, demonstrating good stability and reusability. The use of photovoltaic waste‐derived SiC reduces the dependence on commercial SiC, highlighting the environmental and economic benefits of this sustainable approach. Overall, ZnO@SiC heterojunctions derived from photovoltaic waste offer a sustainable approach for pharmaceutical pollutant removal and photovoltaic waste valorization, supporting circular economy strategies.