Ultrathin Prussian blue analogue nanosheet arrays with open bimetal centers for efficient overall water splitting. (February 2020) - Chen, Ziliang
Abstract: Direct construction of Prussian blue analogues (PBAs) nanosheets arrays as a bifunctional electrocatalyst for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of great significance but still remains challenging. Herein, for the first time, we have proposed an efficient strategy to synthesize Co–Fe bimetallic PBA nanosheet arrays with ultrathin feature and open bimetal centers via one-pot coprecipitation reaction of nickel nitrate and sodium nitroferricyanide in the presence of nickel foam. When employed as the self-supporting bifunctional electrocatalyst, the optimized PBA nanosheet arrays require overpotentials of only 256 and 48 mV to drive 10 mA cm −2 for OER and HER in 1.0 M KOH, respectively. Remarkably, it allows an alkali-electrolyzer with 10 mA cm −2 at a low cell voltage of 1.545 V and a robust operation stability of no less than 36 h. The combination of experimental results and theoretical calculation analysis unravelled that such exceptional electrocatalytic performances could be traced to the ultrathin nanosheet, porous surface structure, and coordinately unsaturated metal centers, enabling abundant active sites, accelerated mass/charge transfer capability, as well as the favorable energy for their transformation to high active Co/Fe-based (oxy)hydroxides during water electrolysis. More broadly, the synthetic strategy is versatile and can be applied to achieve copper foam- and titanium foam-supported bifunctional CoFe-PBA nanosheet electrocatalysts. Graphical abstract: An efficient and versatile strategy is developed to synthesize ultrathin Co–Fe bimetallic Prussian blue analogue nanosheet arrays with open bimetal centers under ambient conditions, which can serve as a highly active bifunctional HER and OER electrocatalyst, enabling an alkali-electrolyzer with a current density of 10 mA cm −2 at a much lower cell voltage compared to that of Pt/C@NF||IrO2 @NF couple. Image 1 Highlights: Prussian blue analogue (PBA) nanosheet arrays with open bimetal centers are synthesized for the first time. The developed PBA exhibits an exceptional bifunctional HER and OER activity. The outstanding performance is unravelled by experimental and theoretical calculation results. The developed synthetic strategy is general.