MXenes@MOFs Hybrid Heterointerfaces for Electrochemical Sensing: Interface Engineering, Progress, Challenges and...

MXenes are fascinating 2D-materials with great potential for electrochemical sensing interfaces owing to their high metallic conductivity, rich surface chemistry, and redox activity. MOFs are unique crystalline structures with ultra-large surface areas and rich adsorption and tunable porous active sites, yet their poor electrical conductivity, charge transport efficiency and chemical and mechanical robustness hinder their practical electrochemical sensing feasibility. Recently, integrating MXenes with MOFs enables designing novel hybrid materials with unique interfacial and synergized properties that resolve this porosity-conductivity trade off. However, engineering MXene@MOFs hybrids with desired heterointerfacial structures and synergized electrochemical sensing properties and behaviors remains under explored. This critical Review discusses the progress of in-situ, ex-situ and derivative methods to engineer MXene@MOFs hybrids with emphasis on interface covalent and non-covalent bonding, distribution of crystallized MOFs into MXenes' interlayer spacing, synergized heterojunctions' formation, and heterointerface sensing mechanism. Moreover, it comprehensively discusses and summaries the progress of these intriguing hybrid materials across wide spectrum of hazardous compounds and environmental pollutants such as antibiotics residuals, heavy metal ions, pesticides, mycotoxins, phenolic, synthetic molecules, and various health related diseases including cancer, amino acids, vitamins, hormones, wearable noninvasive analysis (sweat, saliva, tears and L-cysteine), cardiovascular disease (CVD), glucose, creatinine, and metabolic biomarkers. MXene@MOFs hybrid materials demonstrate unique synergized sensing performance such as the high stability, low signal to noise ratio and lower skin interference impedance compared to Ag/AgCL commercial electrodes. Finally, the sensing mechanism and properties (sensitivity, selectivity, long term stability and reproducibility), commercialization prospects and challenges, future direction and opportunities are discussed.