Defect Engineering To Tailor Metal Vacancies in 2D Conductive Metal-Organic Frameworks: An Example in Electrochemical Sensing

Two-dimensional conductive metal-organic frameworks (2D conductive MOFs) with pi-d conjugations exhibit high electrical conductivity and diverse coordination structures, making them constitute a desirable platform for new electronic devices. Defects are inevitable in the self-assembly process of 2D conductive MOFs. Arguably, defect engineering that deliberately manipulates defects demonstrates great potential to enhance the electrocatalytic activity of this family of novel materials. Herein, a facile and universal defect engineering strategy is proposed and demonstrated for metal vacancy regulation of metal benzenehexathiolato (BHT) coordination polymer films. Controllable metal vacancies can be produced by simply tuning the proton concentration during the confined self-assembly process at the liquid-liquid interface. This facile but universal defect design strategy has been proven to be effective in a class of materials including Cu-BHT, Ni-BHT, and Ag-BHT for physicochemical regulation. To further demonstrate the feasibility and practicality in electrochemical applications, the elaborately fabricated Cu-BHT films with abundant Cu vacancies deliver competitive performance in electrocatalytic sensing of H2O2. Mechanistic analysis revealed that the Cu vacancies act as effective active sites for adsorption and reduction of H2O2, and the tuned electronic structure boosts the electrocatalytic reaction. The developed advanced sensing platform confirms the excellent commercial potential of Cu-BHT sensors for H2O2. The findings provide insights into the molecular structure design of 2D conducting MOFs by defect engineering and demonstrate the commercial potential of Cu-BHT electrochemical sensors.

Automated summary

This paper introduces a novel defect engineering strategy for regulating metal vacancies in metal-organic coordination polymer films, which can enhance their electrocatalytic activity. The experimental results demonstrate that controllable metal vacancies can be produced by simply adjusting the proton concentration. Cu-BHT films with abundant copper vacancies show competitive electrocatalytic performance in sensing H2O2. This finding provides insights into the molecular structure design of 2D conducting MOFs by defect engineering and demonstrates the commercial potential of Cu-BHT electrochemical sensors.