An ultra-sensitive photoelectrochemical sensor based on Sb2WO6/CuO p-n heterojunction for detection of carmine in food

The development of efficient photoelectrochemical (PEC) sensing materials for the food additive carmine (CRM) remains a significant challenge, with no PEC sensor reported for CRM to date. Herein, we reported the first PEC sensor based on an Sb 2 WO 6 /CuO p-n heterojunction for CRM detection. The heterojunction interface facilitated efficient charge separation through an internal electric field, as elucidated by density functional theory calculations. The detection mechanism relied on the specific binding between the carboxyl and hydroxyl groups in CRM molecules and the metal sites on the CuO surface. This interaction blocked the active sites, inhibited hole transfer, and led to a significant decrease in photocurrent. The sensor exhibited a wide linear range (0.4 - 500 μM), a low limit of detection (0.19 μM), and excellent stability (>96.74%). Furthermore, its successful application in beverage samples yielded recovery rates of 97.30 - 101.50%. This work provides a novel PEC platform for sensitive food additive monitoring.