An "On-Site Transformation" Strategy for Electrochemical Formation of TiO₂ Nanoparticles/Ti₃C₂T_x MXene/Reduced Graphene Oxide Heterojunction Electrode Controllably toward Ultrasensitive Detection of Uric Acid

Ascribing to the abundance of Ti element, exceptional electrical conductivity, and electrocatalytic performance, titanium carbide MXene (Ti(3)C(2)Tx, MX) is considered as an ideal conductive matrix and employed for in situ preparation of promising TiO2 NPs@MX/reduced graphene oxide (rGO) heterojunction electrodes for uric acid (UA) detection. However, the incapability of achieving the controllable growth and synthesis of TiO2 nanoparticles (NPs) on MX nanosheets is a bottleneck in fabricating optimal and controllable TiO2 NPs@MX hybrid. Herein, an "on-site transformation strategy" is developed to synthetize TiO2 NPs@MX/rGO heterojunction platform controllably by in situ electrochemical oxidizing MX nanosheets at various treatment times. The proposed approach allows for the greater operability to controllably grow and synthetize TiO2 NPs on the surface of MX nanosheets. The heterojunction electrodes present a linear voltammetric response toward UA in the concentration range of 0.003-0.3 and 0.3-300 mu m and a low detection limit of 0.78 nm (S/N = 3). Additionally, a handheld electrochemical system with a smartphone readout is developed for point-of-care health monitoring, enabling fast, precise, and specific recognition of UA in real urine samples. The study provides a facile and controllable approach to fabricate TiO2 NPs@MX/rGO heterojunction platform for future use in other biomolecules' detection.