Structural and functional role of anions in electrochemical water oxidation probed by arsenate incorporation into cobalt-oxide materials

Abstract

Arsenate ions are incorporated in amorphous cobalt oxide catalysts at the periphery of the lattice or substituting cobalt ions.

Operando Raman spectroscopy tracks oxidation-state changes in an amorphous Co oxide material for electrocatalysis of the oxygen evolution reaction

“…Substituting phosphate for arsenate, x-ray absorption spectroscopy at the As K-edge, recently, has provided support for phosphate binding at the margins of Co oxide fragments. 62 A possible hypothesis is that the 877 cm −1 and 1077 cm −1 solution peaks from H 2 PO 4 − [indicated by dotted red lines in Fig. 1(a)] are broadened and shifted to 924 cm −1 and 1087 cm −1 (solid red lines) when phosphate is trapped in between the Co-oxo clusters.…”

Reversible and irreversible processes during cyclic voltammetry of an electrodeposited manganese oxide as catalyst for the oxygen evolution reaction

“…Furthermore, electrolyte anions may exchange with the deposited films, e.g. [31], which is prevented when the electrolyte composition does not change significantly during deposition and catalytic investigation.…”

A soft molecular 2Fe–2As precursor approach to the synthesis of nanostructured FeAs for efficient electrocatalytic water oxidation

“…The loss of the non-metal in solution is a common phenomenon and has been observed before for transition metal chalcogenides and TMP. 20,26 Moreover, the high solubility of As under oxidizing and alkaline conditions also contributes to its dissolution into the electrolyte. 78 Since a high concentration of As is undesirable due to negative effects on humans and animals, 79 and the environment, 80 the loss of As was quantitatively determined by ICP-AES (see Table S14 †).…”

“…[20][21][22][23][24][25] The transformation occurs either only at the surface of the electrocatalyst forming a core-shell structure or completely throughout the bulk resulting in defect rich and high surface area TM oxides/oxyhydroxides, whereas arsenates have been reported as stable constituents of a Co-based OER catalyst material. 26 TM arsenide electrocatalysts, the heavier congeners, are relatively unknown for the OER except for a recent publication from Schuhmann and co-workers 27 where the high-temperature derived NiAs solid phase was used as an electrocatalyst for an alkaline OER with moderate performance. However, insights on the active structure of arsenide materials remain still unexplored and the structural and functional role of arsenic to catalyse the OER is thus meaningful to evaluate.…”