Abstract
Abstract Copper kesterite Cu2ZnSnS4 is a promising photoabsorber material for solar cells and photoelectrochemical (PEC) water splitting. In this article, we will first review the crystallographic/energetic structures of Cu2ZnSnS4 in view of its applications to sunlight conversion devices. Then, historical progress in photovoltaic properties of Cu2ZnSnS4-based solar cells is introduced. Finally, studies on PEC H2 evolution over Cu2ZnSnS4-based photocathodes are reviewed in detail. For realizing efficient PEC H2 evolution, surface modifications with an n-type buffer layer (such as CdS) and a catalytic site (such as Pt nanoparticles) were found to be indispensable. Since these surface-modified photocathodes had poor resistances under an operating bias due to the occurrence of oxidative photocorrosion of the CdS layer and elimination of the Pt catalysts, coverage with a protection layer was required to improve the long-term durability. Moreover, partial or complete substitution of the constituent cations with some cations was proved to be effective for improving PEC properties. Although recent studies showed a rapid increase in PEC properties, there is room for further development of PEC properties by using effective combinations among surface protection(s), defect engineering(s), and band engineering(s).
Highlights
The energy problem is one of the most important technological problems faced by the world
We investigated PEC H2 evolution by using a chalcopyrite CuInS2 thin film modified with Pt nanoparticles and we achieved a CdS buffer layer (Pt/CdS/CuInS2) and proved a significant enhancement of PEC H2 evolution properties by loading of a chemical bath deposition (CBD)-derived CdS layer [22]
The first application of CZTS as a photocathode was in 2010 by Yokoyama et al, and a photocurrent density of 2.3 mA·cm−2 at 0 VRHE was achieved with a CZTS thin film obtained by sulfurization of an EB-deposited Cu/Sn/ZnS precursor layer modified with CdS and Pt nanoparticles [74]
Summary
The energy problem is one of the most important technological problems faced by the world. A photocatalyst sheet in which SrTiO3:La,Rh and BiVO4:Mo powders are embedded showed a high STH value (1.2%) [16] Since both the single photocatalyst system and Z-scheme system generate a mixture of H2 and O2 gases with a compositional ratio of 2:1, so-called oxyhydrogen detonation gas, installation of an additional separation system such as a separation membrane is required [17]. This is one of the most critical problems of these particulate photocatalystbased systems for their practical use Another promising system using the two-step photoexcitation process is a photoelectrochemical (PEC) cell in which two kinds of semiconductor electrodes, photocathode and photoanode for H2 and O2 evolutions, respectively, are used (Figure 1) [18,19,20]. 448 Shigeru Ikeda aspects of these compounds as well as the operating principle of PEC water splitting, the history of development of CZTS-based photocathodes is overviewed with focus on the surface modifications and substitutions of constituent elements to improve PEC H2 evolution properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
