Inception of Co₃O₄as Microstructural Support to Promote Alkaline Oxygen Evolution Reaction for Co_0.85Se/Co₉Se₈Network

Abstract

Developing electrocatalysts with abundant active sites is a substantial challenge to reduce the overpotential requirement for the alkaline oxygen evolution reaction (OER). In this work, we have aimed to improve the catalytic activity of cobalt selenides by growing them over the self-supported Co3O4 microrods. Initially, Co3O4 microrods were synthesized through annealing of an as-prepared cobalt oxalate precursor. The subsequent selenization of Co3O4 resulted in the formation of a grainy rodlike Co3O4/Co0.85Se/Co9Se8 network. The structural and morphological analysis reveals the presence of Co3O4 even after the selenization treatment where the cobalt selenide nanograins are randomly covered over the Co3O4 support. The resultant electrode shows superior electrocatalytic activity toward OER in alkaline medium by delivering a benchmark current density of 10 mA/cm2 geo at an overpotential of 330 mV. As a comparison, we have developed Co0.85Se/Co9Se8 under similar conditions and evaluated its OER activity. This material consumes an overpotential of 360 mV to deliver the benchmark current density, which signifies the role of the Co3O4 support to improve the electrocatalytic activity of Co0.85Se/Co9Se8. Despite having a low TOF value for Co3O4/Co0.85Se/Co9Se8 (0.0076 s–1) compared to Co0.85Se/Co9Se8 (0.0102 s–1), the improved catalytic activity of Co3O4/Co0.85Se/Co9Se8 is attributed to the presence of a higher number of active sites rather than the improved per site activity. This is further supported from the C dl (double layer capacitance) measurements where Co3O4/Co0.85Se/Co9Se8 and Co0.85Se/Co9Se8 tender C dl values of about 8.19 and 1.08 mF/cm2, respectively, after electrochemical precondition. As-prepared Co3O4/Co0.85Se/Co9Se8 also manifests rapid kinetics (low Tafel slope ∼ 91 mV/dec), long-term stability, low charge-transfer resistance, and 82% Faradaic efficiency for alkaline electrocatalysis (pH = 14). Furthermore, the proton reaction order (ρRHE) is found to be 0.65, indicating a proton decoupled electron transfer (PDET) mechanism for alkaline OER. Thus, the Co3O4 support helps in the exposure of more catalytic sites of Co0.85Se/Co9Se8 to deliver the improved catalytic activities in alkaline medium.

Anion‐Doping‐Induced Vacancy Engineering of Cobalt Sulfoselenide for Boosting Electromagnetic Wave Absorption

“…On the one hand, compared with the Co‐based precursor, it is reported that the as‐prepared spinel Co 3 O 4 can facilitate the reconstruction of the sublattice via reducing the energy gap during selenization that further promote the formation of metal selenides. [ 22 ] Noted that the metal selenides possess the better electronic conductivity than the corresponding oxides or sulfides, this advantage can endow us with more room to modulate EM parameter and optimize EMW absorption capacity. On the other hand, the lattice oxygen in spinel Co 3 O 4 can be substituted by the S and Se via ion exchange in the subsequent sulfuration/selenization treatment.…”

Influence of Vanadate Structure on Electrochemical Surface Reconstruction and OER Performance of CoV2O6 and Co3V2O8

“…CoV 2 O 6 exhibited 89% efficiency for the OER process (Figure S9), and proton reaction order (ρRHE) determination for OER involving CoV 2 O 6 revealed the reaction to primarily proceed through a proton decoupled electron transfer pathway (Figure S10). 23 To better comprehend the postcatalytic state of the materials, they were first subjected to prolonged chronopotentiometry that showed near-constant performance (Figure S11) followed by structural and morphological investigations. The pXRD patterns of both materials showed a peak at 2θ = ∼11.5°(Figure S12).…”

Nickel–cobalt oxalate as an efficient non-precious electrocatalyst for an improved alkaline oxygen evolution reaction

“…[16][17][18] There are quite a few literatures on non-precious non-oxide electrocatalyst for alkaline OER application such as Co 4 N, (Co 0.7 Fe 0.3 ) 2 B, (Co x Fe 1-x ) 2 P and Co 0.85 Se/Co 9 Se 8 etc. [19][20][21][22] Thus, non-precious non-oxide electrocatalyst stimulates great attention for alkaline OER.…”