Efficient Electrochemical Reconstruction of a Cobalt- and Silver-Based Precatalytic Oxalate Framework for Boosting the Alkaline Water Oxidation Performance

Abstract

The quest toward finding an efficient oxygen evolution reaction (OER) catalyst utilizing a sustainable and facile synthetic strategy is still underway. Low overpotential, better stability, and rapid kinetics are the key features to be considered while designing a competent OER catalyst. Herein, we have developed a rapid and efficient wet chemical route for the synthesis of a cobalt-and silver-based precatalytic oxalate (CoC 2 O 4 /Ag 2 C 2 O 4 ) framework via a rapid precipitation method at room temperature. The optimized catalyst required an overpotential of 260 mV to reach the benchmark current density of 10 mA/cm 2 geo , with a Tafel slope value of 47 mV/dec. It has also shown 72 h of chronopotentiometry stability as well as 1000 cycles of potentiodynamic stability along with 90% Faradaic efficiency in 1(M) KOH for OER. Addition of a minimal amount of silver component assists in the reduction of overpotential up to 120 mV compared to CoC 2 O 4 . Furthermore, the minimal amount of silver inclusion improved the charge migration property via lowering the charge-transfer resistance besides tuning the charge storage mechanism (b value). The paradigm shift in catalytic efficiency can be manifested by calculating both intrinsic (persite activity) and geometric (based on the effective area of electrode materials) activities. Interestingly, significant improvement in C dl (double-layer capacitance) from 10.25 to 19.59 mF/cm 2 is achieved upon silver component inclusion, indicating a higher number of accessible catalytic sites for alkaline OER. The turnover frequency value further authenticates the importance of silver component in the precatalytic oxalate network for intrinsic catalytic activity under alkaline conditions. The mechanistic trajectory is also investigated from the proton reaction order (ρRHE), revealing the occurrence of the proton-decoupled electron transfer process for the optimized catalyst. The results reveal the efficient electrochemical surface reconstruction in the cobalt-and silver-based precatalytic oxalate framework for improved alkaline water oxidation through exposing the surface as well as bulk active centers for easy electrolyte diffusion in alkaline medium.

Evolution of Carbonate‐Intercalated γ‐NiOOH from a Molecularly Derived Nickel Sulfide (Pre)Catalyst for Efficient Water and Selective Organic Oxidation

“…[ 43 ] Elemental mapping shows a homogeneous distribution of Ni and O, indicating the formation of oxidic Ni active phase and the presence of adsorbed K on the surface, which could be due to residual KOH electrolyte (Figure S37, Supporting Information). [ 44 ] Additionally, the EDX spectrum after CP at 500 mA cm −2 for 10 h also reveals complete leaching of S, which is consistent with the findings after 24 h OER CP at 10 mA cm −2 (Figures S38 and S39, Supporting Information). Furthermore, a close examination of TEM images corroborates the microstructural transformation, revealing a sheet‐like morphology after OER, like the findings from SEM images ( Figure a, Figures S34 and S40, Supporting Information).…”

Oxalate metal–organic framework derived atomic Ru3+-doped Co(OH)2nanosheets for a highly efficient hydrogen evolution reaction

“…32 The threedimensional structure of CoC 2 O 4 is stacked by onedimensional (1D) chains. 33 34,35 The diffraction peaks at 19°, 32°, 38°, 51°and 58°correspond to the 36,37 respectively, are shied to lower binding energy, as compared with those of pure Co(OH) 2 (Fig. 2D).…”

“…32 The three-dimensional structure of CoC 2 O 4 is stacked by one-dimensional (1D) chains. 33 Furthermore, we synthesized a series of Ru-doped oxalate MOFs with different Ru contents, Ru-CoC 2 O 4 -1, Ru-CoC 2 O 4 -2 and Ru-CoC 2 O 4 -3, through a one-pot hydrothermal process. As evidenced by the XRD patterns, all the Ru-CoC 2 O 4 MOFs have a similar crystal structure to CoC 2 O 4 .…”

Waste to Treasure: Regeneration of Porous Co-Based Catalysts from Spent LiCoO2 Cathode Materials for an Efficient Oxygen Evolution Reaction

“…The CV result indicates the in situ formation of Co(OH) 2 on the surface of Co 9 S 8 and further reconstruction of CoOOH before the OER process. As shown in Figure S20c,f,i, the Raman bands located at 465 (464) cm –1 and 673 (664) cm –1 demonstrate the presence of CoOOH in Co 3 O 4 , Co/Co 3 O 4 , and Co 9 S 8 …”

“…Electrochemical impedance spectroscopy (EIS) was applied to evaluate the electron transfer kinetics of the catalysts. Figure 4f shows the Nyquist plot fitted with an equivalent circuit (inset in Figure 4f 38 The exceptional OER performance of Co 9 S 8 /Co 3 O 4 can be assigned to the synergetic effect of the diverse porous architecture and heterojunction structures. On the one hand, the diverse porous architecture contains macropores and mesopores, where macropores provide quick pathways for the reactant and product and mesopores can contribute more active sites on the surface.…”