Heterointerface-Engineered NiCo ₂ O ₄ /Ti ₃ C ₂ T _X Nanohybrids for Electrochemical Detection of Hydrogen Peroxide

Hydrogen peroxide (H 2 O 2 ) is a key reactive species in physiological pathways and environmental systems; however, its abnormal accumulation poses serious risks to human health, underscoring the need for highly sensitive, reliable, and enzyme-free detection platforms. Herein, we report the rational design of NiCo 2 O 4 /Ti 3 C 2 T X (MXene) nanohybrids as advanced nanoscale electrocatalysts for nonenzymatic H 2 O 2 sensing. The nanohybrids were synthesized via a one-step hydrothermal strategy, in which the introduction of Ti 3 C 2 T X nanosheets modulates the crystallization and growth kinetics of NiCo 2 O 4, directing the formation of hierarchical urchin-like and sheet-like microflower architectures composed of ultrathin nanosheets. This nanoscale structural organization markedly enhances electron transport, electrolyte penetration, and exposure of catalytically active sites. The optimized NiCo 2 O 4 /Ti 3 C 2 T X electrode exhibits a wide linear detection range of 1–110 μM with a sensitivity of 9.31 μA μM –1, while increased MXene loading further improves the sensitivity to 27.82 μA μM –1 over a linear range of 1–80 μM. The superior electrocatalytic performance arises from the high electrical conductivity of Ti 3 C 2 T X nanosheets, the abundance of redox-active sites in NiCo 2 O 4 and strong interfacial coupling within the heterostructured nanohybrid. Density functional theory (DFT) calculations reveal enhanced H 2 O 2 adsorption (−1.4 eV) and accelerated interfacial charge transfer at the NiCo 2 O 4 /Ti 3 C 2 T X interface compared with pristine NiCo 2 O 4 (−1.1 eV), in excellent agreement with experimental results. Moreover, the sensor demonstrates outstanding stability, reproducibility, and selectivity toward common interferents, along with successful applicability in biological and food samples.