Electrochemical Water Oxidation Catalyzed by an In Situ Generated α‐Co(OH)₂ Film on Zeolite‐Y Surface

Abstract

The design and synthesis of an efficient and robust water-oxidation catalyst with inexpensive materials remains an important challenge in the context of artificial photosynthesis. Herein, as imple but unique technique is reported to in situ generate at hin-film of a-Co(OH) 2 on the surface of zeolite-Y [hereafter referred to as Y-a-Co(OH) 2 ] that acts as an efficient and stable catalyst for electrochemical water oxidation in alkaline medium. Catalyst Y-a-Co(OH) 2 is so stable that it retains its catalytic activity even after 2000 cyclic voltammetric cycles of water oxidation. Expectedly,t he chemical compositiono fa-Co(OH) 2 on the surface of zeolite-Y remainss ame as that of parentY -a-Co(OH) 2 after 2000 electrocatalytic cycles. AT afel slope as low as 59 mV decade À1 in 0.1 m KOH (pH 13) suggestsf aster oxygen evolution kinetics (overpotential = 329 mV;t urnover frequency = 0.35 mol O 2 (mol Co)À1 s À1 at 1mAcm À2 )t han the existing aCo(OH) 2 -based electrocatalysts operating in alkaline medium.

A Keggin Polyoxometalate Shows Water Oxidation Activity at Neutral pH: POM@ZIF‐8, an Efficient and Robust Electrocatalyst

“…[1][2][3][4][5][6][7] Recently enormous efforts have been devoted to prepare first-row transition-metal-ion (particularly,c obalt)-based inexpensive WOCs. [8][9][10][11][12][13][14][15][16][17][18] Development of polyoxometalates (POMs) as WOCs came as am ajor breakthrough in this regard. [19][20][21][22][23][24][25][26][27] Thek ey structural features of POMs for POM-WOCs are their complete inorganic skeleton and the scope of fast, reversible electron transfer (resulting into fast WO kinetics).…”

A Keggin Polyoxometalate Shows Water Oxidation Activity at Neutral pH: POM@ZIF‐8, an Efficient and Robust Electrocatalyst

“…[4,5] In last few decades, various research groups have contributed towards understanding of the process of WO and designing of robust and efficient WOCs. [8][9][10][11][12][13][14][15][16][17][18] Development of polyoxometalates (POMs) as WOCs came as am ajor breakthrough in this regard. [8][9][10][11][12][13][14][15][16][17][18] Development of polyoxometalates (POMs) as WOCs came as am ajor breakthrough in this regard.…”

Cobalt based functional inorganic materials: Electrocatalytic water oxidation

“…In fine, we can say that Co-WOC-1 demonstrates a unique example of a water oxidation catalyst from a structural point 33 of view. Even though it operates best in high pH, it has very good TOF and high Faradaic efficiency.…”

“…In recent times, we have been exploring cobalt-based functional materials including MOFs, polyoxometalates (POMs) and zeolites for electrochemical water oxidation. 33,48,49 The present article describes our recent findings on electrochemical water oxidation catalysed by these cobaltbased materials, which were presented in the MTIC-XVII meeting, held in Pune during December 11-14, 2017.…”

“…The efficiency of such CoO x /Co(OH) x system depends largely on the morphology of the system, particle size and operational pH. 33 Since such materials are all heterogeneous catalysts, these are easier to work with and thus have been able to attract a lot of attention in the recent years. At the same time, these results have raised questions about the authenticity and importance of many molecular compounds which were earlier proposed to be the true catalyst.…”