A cobalt hydroxide coated metal-organic framework for enhanced water oxidation electrocatalysis

Metal–Organic Frameworks for Electrocatalysis: Beyond Their Derivatives

“…d–f) Reproduced with permission. [ 72 ] Copyright 2021, Elsevier Inc. g) Cyclic curves of Bi(btb) at 50 mV s −1 in Ar‐ and CO 2 ‐saturated 0.5 m KHCO 3 solutions (inset: how the value of E onset was determined). h) CO 2 RR results at various potentials in CO 2 ‐saturated electrolytes based on 30 min tests.…”

“…[ 71 ] In 2021, Yao et al reported an in situ cathodic electrotransformation method to synthesize a cobalt hydroxide‐coated Co‐MOF (named Co(OH) 2 /Co‐MOF) as the latest precious‐metal‐free MOF‐HGCCs for OER electrocatalysis (Figure 13d–f). [ 72 ] Experimental analysis and DFT calculations revealed that the enhanced OER performance of the as‐prepared material including long‐term stability and high activity with an overpotential of 196 mV at 10 mA cm −2 for 15 h continuous testing in a 1 m KOH solution was ascribed to the tailored adsorption free energy of oxygenic intermediates and unique structure with abundant exposed active centers and well‐tuned gas release ability. This work laid the foundation for the future design of MOFs with coordinatively saturated metal centers for OER.…”

Realizing electrochemical transformation of a metal–organic framework precatalyst into a metal hydroxide–oxy(hydroxide) active catalyst during alkaline water oxidation

“…72 The structural evolution of the MOF into ultrathin M(OH) 2 -M(O) x (OH) y nanosheets was also conrmed for NiFc-MOF and Co-MOF-Co(OH) 2 by PXRD studies. 76,111 The electrochemical transformation of PBA into ultrathin M(OH) 2 -M(O) x (OH) y nanosheets can also be determined by IR spectroscopic studies. The IR peaks assigned to the -CN group in CoCo-PBA totally disappeared during water oxidation.…”

“…[67][68][69][70][71][72][73][74] In these cases, the MOF plays the role of a precatalyst and undergoes a series of structural reconstruction and selfassembly processes during the OER to form ultrathin M(OH) 2 -M(O) x (OH) y nanosheets. 36,56,58,[61][62][63]69,[75][76][77][78] MOFs have several advantages as a precatalyst like (i) the synthesis of MOFs is easy, facile, and scalable, (ii) the structural and electronic properties of MOFs can be easily tuned, (iii) MOFs undergo bulk and complete electrochemical transformation to form ultrathin M(OH) 2 -M(O) x (OH) y nanosheets and (iv) the required time for the electrochemical transformation is surprisingly low (few seconds to minutes). 7,9,12,79,80 Another advantage of using MOFs as the precatalyst comes from the formation of a self-supported catalyst system, which provides enhanced electronic conductivity, improved charge transport, and strong catalyst-support interaction.…”

“…62 The electrochemically synthesized M(OH) 2 -M(O) x (OH) y nanosheets show atomic-level thickness, a large electrochemical surface area, a tuned electronic structure, and a large number of accessible active sites. 36,56,58,[61][62][63]69,[75][76][77][78] In addition, a self-supported catalyst system with improved charge transport, high mechanical stability, and strong catalyst-support interaction has been achieved by the electrochemical transformation approach. Hence, the activity and the stability of the catalyst are dramatically improved for water oxidation.…”