High-Performance Transition Metal Phosphide Alloy Catalyst for Oxygen Evolution Reaction

Abstract

Oxygen evolution reaction (OER) is a pivotal process in many energy conversion and storage techniques, such as water splitting, regenerative fuel cells, and rechargeable metal-air batteries. The synthesis of stable, efficient, non-noble metal-based electrocatalysts for OER has been a long-standing challenge. In this work, a facile and scalable method to synthesize hollow and conductive iron-cobalt phosphide (Fe-Co-P) alloy nanostructures using an Fe-Co metal organic complex as a precursor is described. The Fe-Co-P alloy exhibits excellent OER activity with a specific current density of 10 mA/cm being achieved at an overpotential as low as 252 mV. The current density at 1.5 V (vs reversible hydrogen electrode) of the Fe-Co-P catalyst is 30.7 mA/cm, which is more than 3 orders of magnitude greater than that obtained with state-of-the-art Fe-Co oxide catalysts. Our mechanistic experiments and theoretical analysis suggest that the electrochemical-induced high-valent iron stabilizes the cobalt in a low-valent state, leading to the simultaneous enhancement of activity and stability of the OER catalyst.

A Room‐Temperature Postsynthetic Ligand Exchange Strategy to Construct Mesoporous Fe‐Doped CoP Hollow Triangle Plate Arrays for Efficient Electrocatalytic Water Splitting

“…And the Co 2p 3/2 spectrum (Figure b, red curve) with a predominate peak located at 780.1 eV can be indexed to the Co species in CoOOH . The Fe 2p 3/2 spectrum (Figure c, red curve) with a broad peak centered at about 711.1 eV can be assigned to Fe species in FeOOH . Furthermore, the HRTEM image in Figure S15 in the Supporting Information shows that some oxidation species are formed.…”

Preparation of Yolk–Shell‐Structured CoxFe1−xP with Enhanced OER Performance

“…Structure and composition of Co x Fe 1Àx Pm icrospheres [9] These can be attributed to ac omposite phosphide phase with aC oP-like structure. Compared to XRD patterns of cobalt ferrite precursors ( Figure S1 in the Supporting Information), no diffractionp eaks forc obalt ferrites are observed for Co x Fe 1Àx P. This indicates that Co x Fe 1Àx P was successfully synthesized by phosphiding cobalt ferrites.…”

“…[4] However,t heir applicationh as been greatly limitedb yt heir small reserves and high costs.I ti sn ecessary to develop OER catalysts with low cost, abundant reserves, and superior performance. [6] Various metal oxides and metal hydroxides,i ncluding cobalt oxides, [2c, 7] Ni-Co oxides, [8] Ni-Fe-Co oxides, [9] nickelh ydroxides, [10] andC o-Cr hydroxides [11] have been intensively studied as OER catalysts. [6] Various metal oxides and metal hydroxides,i ncluding cobalt oxides, [2c, 7] Ni-Co oxides, [8] Ni-Fe-Co oxides, [9] nickelh ydroxides, [10] andC o-Cr hydroxides [11] have been intensively studied as OER catalysts.…”

“…[14] More recently,m etal sulfides have been used as OER catalysts because of their betterintrinsic electrical conductivity.S hanmugam and co-workers prepared CoS 2 (400)/N, S-GO, which showedb etter electrocatalytic performance than preciousm etal catalysts. [9,17] Recently,t ransition metal phosphidesh ave attracted researchers because of their excellent OER properties [9] (e.g.,h igh activity,o utstanding durability,a nd low cost). [16] Although metal sulfides show higher OER performance, their poor structural stabilityd uring the OER process limits their implementation in OER-related applications.…”

An Intriguing Pea‐Like Nanostructure of Cobalt Phosphide on Molybdenum Carbide Incorporated Nitrogen‐Doped Carbon Nanosheets for Efficient Electrochemical Water Splitting

“…[66] In addition, amorphization at the surfaceo ft he particles can be observed in FigureS19 ai nt he Supporting Information. [67] It is worth noting that significant loss of Mo after catalysis is observed through ICP-OES analyses, through which the atomic ratio of Co/Mo increasedf rom 1.05 to 10 and 40 after the HER and OER, respectively (Table S1 in the SupportingI nformation). In addition, the generation of CoOOH is confirmed by fringe spacings of 0.23 and 0.216 nm for (111)a nd (200) crystal planes, respectively (Figure S19 bi nt he Supporting Information).…”