Recent years have seen unprecedented motivation for the emergence of new energy technologies. The global energy dependence on fossil fuels, however, will persist until alternate technologies can be achieved economically. We must develop means to produce energy (or energy carriers) from renewable sources and then convert them to work as efficiently and cleanly as possible. In this talk, several recent progresses on electrocatalytic based energy conversion from carbon dioxide and water, and redox reaction based energy storage of electricity (that is, batteries and supercapacitors) will be highlighted and discussed. The central theme of these studies is the interplay of fundamental mechanistic studies and materials design: first-principles-based calculations and well-defined experimental model systems are the keys to identify the scientific principles governing the catalyst/electrode behavior, based on which the rational design of catalyst/electrode materials are carried out for achieving high-performance.