Valizadeh, Amirreza Bikas, Rahman Nandy Subhajit Lis, Tadeusz Chae, Keun Hwa Najafpour, Mohammad Mahdi 2024-01-19T13:01:29Z 2024-01-19T13:01:29Z 2022-04-03 2022-01 1477-9226 https://pubs.kist.re.kr/handle/201004/115839 A cobalt coordination compound with azo-ligand linkers combined with linked bisulfonate moieties has been argued to be an efficient catalyst for the oxygen-evolution reaction (OER) (H.-T. Shi, X.-X. Li, F.-H. Wu and W.-B. Yu, Dalton Trans., 2017, 46, 16321.). In the previously published report, this cobalt compound (compound 1) was believed to display a high turnover frequency (5 s(-1)) at eta = 720 mV at pH 9. Herein, the OER in the presence of compound 1 is reinvestigated. The nanosized oxide-based particles formed after the OER in the presence of compound 1 were tracked by electrochemical methods, scanning electron microscopy (SEM), energy dispersive spectrometry (EDX), X-ray diffraction studies (XRD), (High-resolution) transmission electron microscopy ((HR)TEM), Raman spectroscopy, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS). Based on these experiments, it is proposed that a candidate for the true catalyst of the OER in the presence of compound 1 is cobalt oxide. During the OER and using chronoamperometry, the oxidation state of Co ions for the formed Co oxide is (III), but after consecutive CVs the oxidation states of Co ions for the formed Co oxide are (II) and (III). The results shed new light on the role of Co oxide nanoparticles formed in the presence of this Co coordination compound during the OER. Our experimental data also show that for the OER in the presence of a homogeneous (pre)catalyst, careful analyses to find the role of metal oxides are necessary for informed progress. The present findings also might help to find the mechanism of the OER in the presence of coordination compounds. English Royal Society of Chemistry Homogeneous or heterogeneous electrocatalysis: reinvestigation of a cobalt coordination compound for water oxidation Article 10.1039/d1dt03036a 1 Dalton Transactions, v.51, no.1, pp.220 - 230 Dalton Transactions 51 1 220 230 N scie scopus 000728259200001 2-s2.0-85121645854 Chemistry, Inorganic & Nuclear Chemistry Article; Early Access IN-SITU OXYGEN EVOLUTION MANGANESE OXIDE NEUTRAL PH ELECTROCHEMICAL REDUCTION POLYOXOMETALATE CATALYST IRON COMPLEXES PHOTOSYSTEM-II PORPHYRIN ELECTRODE