Recent Advances in Nanoparticles Confined in Two-Dimensional Materials as High-Performance Electrocatalysts for Energy-Conversion Technologies

Recently, the fast-growing advanced electrochemical energy-conversion technologies for environmentally friendly production or utilization of energy requires highly active and stable electrocatalysts and many strategies have been accordingly proposed to achieve this goal. Of them, confinement strategy holds great potential because it can create unique microenvironment for electrocatalysts. Thanks to the exceptional physical and chemical properties, the two-dimensional materials (2D materials) as building block are powerful in constructing inimitable "confined space" which will endow electrocatalysts with many intriguing characteristics, such as admirable electron conductivity, enhanced stability and anti-poisoning capability, and more accessible active sites as well. Despite numerous efforts have been devoted and some progress has been made in confinement research, there exist substantial challenges to be tackled with regard to respectable activity, stability, and mass production of the confined electrocatalysts. In this Minireview, the concept of "nanoparticles confined in two-dimensional materials (denoted as NCTDM)" and their up-to-date synthetical strategies, including host-guest assembly method and in-situ formation method have been firstly discussed. In addition, with special emphasis on their application, the NCTDM as a new type of high-performance electrocatalysts for electrochemical energy-conversion technologies such as water splitting, fuel cells and electrochemical reduction of CO2 to C-1 molecules have been systematically introduced.