Cobalt Incorporated Hydroxyapatite Catalyst for Water Oxidation

Abstract

We report the novel oxygen evolution reaction (OER) catalyst based on cobalt incorporated hydroxyapatite (CoHAP). Our catalyst is prepared on the surface of hydroxyapatite by ion exchange reaction in Co2+ aqueous solution. The cobalt content is approximately 1 wt. % based on ICP‐AES and XPS experiments. XRD, TEM, EDX experiments suggest that individual cobalt ions are adsorbed on the HAP surface in non‐aggregated manner. The cyclic voltammetry (CV) of CoHAP exhibits a weak oxidation peak at 1.10 V which is comparable to CV of in‐situ formed Co−Pi in previous literature. Tafel slope is approximately 80 mV/decade which is independent on the loading amount of CoHAP. The Faradaic efficiency is 94 % measured by quantitative analysis of O2 using gas chromatography. Bulk electrolysis verifies that CoHAP can be utilized OER catalyst at neutral pH with high stability. Our preparation method using hydroxyapatite as a solid phase phosphate source offers a new strategy to fabricate the OER catalysts.

Permanently polarized hydroxyapatite, an outstanding catalytic material for carbon and nitrogen fixation

“…38–41 More specifically, the ion-exchange method has been used to prepare supported HAp metallic catalysts. For example, the incorporation of copper, 40 palladium, 41 ruthenium 42 and cobalt 43 has been successfully used to catalyze the degradation of toxic organic pollutants, the low-temperature methane (CH 4 ) combustion, the cleavage of aromatic ether groups and the water oxidation. On the other hand, surface OH − anions from HAp nanowires were used to fix cobalt-based metal–organic framework and promote the catalytic degradation of organic pollutants.…”

Concurrent occurrence of electrochemical dissolution/deposition of cobalt–calcium phosphate composite

“…OER catalytic property of CoHAP is recently reported in neutral pH condition. 23 Concurrently, calcium and phosphate ions produced from HAP dissolution recombine with cobalt ions or reactive oxygen species from water oxidation. Recombination of these ions results in precipitation of the CCPC film on the surface of ITO.…”

A “Zero-Cost” Adsorbing Hydroxyapatite-Based Material from Amazon Fishery Waste for Water Remediation and Nutrient Release for Agriculture

“…On the other hand, similar adsorption capacities among the different hydroxyapatite-based materials were found for Co 2+ . Cobalt ion removal from aqueous solutions by hydroxyapatite has already been reported to take place mainly by ion exchange with calcium [130][131][132][133][134] and therefore, Co 2+ adsorption on all HAp samples is supposed to be facilitated. Nonetheless, physisorption always overlaps to ion exchange causing adsorption to occur through different pathways and resulting in a less stable kinetic profile (more significant deviations).…”