Current Mechanistic Understanding of Surface Reactions over Water-Splitting Photocatalysts

Abstract

Solar water splitting for hydrogen generation over semiconductor photoelectrodes is a promising solution to the energy crisis and environmental issues. Because complex physical, chemical, and electrical processes are involved in solar energy conversion reactions, understanding the mechanisms is of great significance for the rational design of highly efficient solar water-splitting cells. This review describes the current mechanistic understanding of the adsorption of reactants, injection of charge carriers, and desorption of products during surface redox reactions. Variations of interfacial band-gap structures, the status of surface bonding, and the behavior of charge carriers in semiconductor photoelectrodes are discussed. This review could inspire further innovative work on understanding the mechanisms of solar water splitting.

Redox-Based Visible-Light-Driven Z-Scheme Overall Water Splitting with Apparent Quantum Efficiency Exceeding 10%

“…Particulate-based solar water splitting is a promising and economically feasible technology to convert solar energy considering its simplicity and easy scalability. [1][2][3][4] To date, two kinds of systems have been developed for this purpose: one is called the one-step photo-excited system and the other is known as the twostep photo-excited system (also called the Z scheme). 1,5 Regardless of one-step or two-step photo-excited process, the construction of overall water splitting (OWS) systems has always confronted huge challenges from both thermodynamic and kinetics aspects because it inevitably involves the four-electron transferred water oxidation uphill reaction.…”

Ti, Zn co-doped hematite photoanode for solar driven photoelectrochemical water oxidation

“…As one of the methods, photoelectrochemical cell device, which has been developed to address this problem by using solar energy more efficiently, can split water to oxygen and hydrogen, thus transferring unstable solar energy to storable chemical energy [1][2][3][4] . Numerous semiconductors, including TiO 2 , WO 3 , BiVO 4 and α-Fe 2 O 3 [5][6][7][8][9] , have been studied as photoanode materials in PEC systems. Recently, several studies have proved that α-Fe 2 O 3 [5][6][7][8] is a promising photoanode toward water splitting as a result of high stability in alkaline solutions, narrow band gap (1.9-2.2 eV) [5] , proper valance band position and earth abundant [6] .…”

Research advances towards large-scale solar hydrogen production from water

“…The magnitude of the extra energy is determined by surface chemistry of the photocatalyst. 21 It adds to the required VBM/CBM and hence minimum Eg. Second, it is difficult to predict, measure, and tune the VBM and CBM separately.…”