Core–Shell Prussian Blue Analogs with Compositional Heterogeneity and Open Cages for Oxygen Evolution Reaction

Abstract

Here, a reduction‐cation exchange (RCE) strategy is proposed for synthesizing Fe–Co based bimetallic Prussian blue analogs (PBAs) with heterogeneous composition distribution and open cage nanocage architecture. Specially, bivalent cobalt is introduced into a potassium ferricyanide solution containing hydrochloric acid and polyvinyl pyrrolidone. The uniform PBAs with opened cages are formed tardily after hydrothermal reaction. Time‐dependent evolution characterization on composition elucidating the RCE mechanism is based on the sequential reduction of ferric iron and cation exchange reaction between divalent iron and cobalt. The PBA structures are confirmed by electron tomography technology, and the heterogeneous element distribution is verified by energy‐dispersive X‐ray spectroscopy elemental analysis, leading to the formation of core–shell PBAs with compositional heterogeneity (Fe rich shell and Co rich core) and open cage architecture. When the PBA catalysts are used to boost the oxygen evolution reaction (OER), superior OER activity and long‐term stability (low overpotential of 271 mV at 10 mA cm −2 and ≈5.3% potential increase for 24 h) are achieved, which is attributed to the unique compositional and structural properties as well as high special surface areas (576.2 m 2 g −1 ). The strategies offer insights for developing PBAs with compositional and structural multiplicity, which encourages more practical catalytic applications.

Rapid and Scalable Synthesis of Prussian Blue Analogue Nanocubes for Electrocatalytic Water Oxidation†

“…During the past few years, the Prussian blue analogue (PBA)‐based compounds with coordinated metal sites linked by the cyano groups have been developed as efficient catalysts for OER. [ 57‐65 ] Galan‐Mascaros and co‐workers proposed a phase conversion strategy for transforming Co(OH) 1.0 (CO 3 ) 0.5 · n H 2 O into CoFe PBA thin film, resulting in improved OER activity in a wide pH range. [ 61 ] Wang group developed a confined heat treatment approach for the fabrication of NiFe PBA nanocrystals with high OER activity.…”

“…[ 62 ] Li group reported a core‐shell PBA nanostructured catalyst with open nanocage morphology, which achieves improved OER performance with synergistic benefits of large surface area and optimal composition. [ 63 ] Chen group fabricated a ternary catalyst based on NiCoFe PBA with hollow multivoid nanocuboid morphology, which exhibits enhanced activity towards bifunctional oxygen evolution and hydrogen evolution. [ 64 ] To date, rapid, scalable and universal synthesis approach of the PBA‐based catalysts with tunable compositions and uniform particle size is still urgently demanded, and the related elucidation of the pre‐oxidation process prior to OER catalysis is also needed.…”

Spherical Ni3S2/Fe‐NiPx Magic Cube with Ultrahigh Water/Seawater Oxidation Efficiency

“…[ 26 ] However, most of the reported PBA‐derived nanomaterials focus on homogenous single‐phase structures or single‐anionic bimetallic heterostructures, which partially limits their electrocatalytic performance and electrical conductivity. [ 27 ] The design of the double anionic heterostructure can compatibly integrate the advantages of differentiated components, which allows precise control of the catalytic activity and other physiochemical properties of the material.…”

Old Materials for New Functions: Recent Progress on Metal Cyanide Based Porous Materials

“…Another strategy of increasing compositional heterogeneity and complexity was demonstrated by building heterogeneous hollow core–shell structure of Co–Fe PBA through one‐pot synthesis (reduction‐cation exchange strategy). [ 50 ] The Fe III in Co 3 [Fe III (CN) 6 ] 2 nanocubes were reduced by PVP to Fe II species, which etched the face‐center positions and formed a shell of Fe II 3 [Fe III (CN) 6 ] 2 due to the lower K sp . Therefore, a complex nanoarchitecture (PBA‐5) composed of Fe‐rich shell and Co‐rich core was successfully synthesized, which enabled high surface area of 576.2 m 2 g −1 and high OER catalytic performance.…”