Hybrid 0D/2D edamame shaped ZnIn2S4 photoanode modified by Co-Pi and Pt for charge management towards efficient photoelectrochemical water splitting

Charge separation and transport as well as light absorption are pivotal in determining the efficiency of solar water splitting devices. Herein, we have designed a novel edamame shaped ZnIn2S4 nanostructures consisted of hybridized nanoflakes (2D) and nanoparticles (0D) on ITO conductive substrate through a simple hydrothermal method for PEC water splitting for the first time. The growth mechanism of 0D/2D ZnIn2S4 is proposed and discussed in detail. The series of PEC measurements indicate that edamame shaped 0D/2D ZnIn2S4 films exhibit relatively higher PEC activity (0.37 mA/cm2 at 1.23 V vs. RHE) than that of ZnIn2S4 NFs and ZnIn2S4 NPs due to the enhanced light absorption and efficient charge separation and transfer and increased active sites. Additionally, after selectively depositing Co-Pi cocatalyst and Pt NPs on the top and bottom sides of edamame shaped ZnIn2S4 photoanodes, charge recombination at the surface and interface can be efficiently reduced. The spatial Co-Pi cocatalyst drives holes to flow to the surface, while the Pt NPs facilitate the electrons in the opposite directions. Thus, the integrated Co-Pi/ZnIn2S4/Pt equipment without any additional doping presents an increased photocurrent density with 0.91 mA/cm2 at 1.23 V vs. RHE. This work highlights that edamame shaped ZnIn2S4 can be a promising candidate for photoelectrochemical behavior and rout such as coupling of Co-Pi and Pt co-catalysts on photoanodes have an interfacial electric field can provide a new avenues to design efficient PEC devices in future.