ABSTRACT
Free-standing electrocatalysts (FSECs) are a series of electrochemically active materials grown directly on a substrate with remarkable conductivity, sufficient porous structure, and high specific surface areas. The catalytic properties of FSECs toward both hydrogen and oxygen evolution reactions (HER/OER) for alkaline water electrolysis mainly depend on the substrates, active materials, and synthesis methods of FSECs. In this chapter, we first introduce the concepts, advantages, and relative mechanisms of FSECs. Then, the merits and applications of different substrates (such as the nickel foam and carbon fiber paper carbon cloth) for FSECs are summarized and introduced. Importantly, we reviewed the various active materials of FSECs for both HER and OER, including metals or alloys, transitional metal oxides, transitional metal sulfides, transition metal selenides, transition metal phosphides, transition metal carbides and nitrides, transition metal hydroxides/oxyhydroxides, and indicated their advantages and shortcomings. Lastly, some typical synthesis methods of FSECs are summarized and reviewed. This chapter can shed the light on the development of high-performance FSECs.
