Approach to Evaluation of Electrocatalytic Water Splitting Parameters, Reflecting Intrinsic Activity: Toward the Right Pathway

Cobalt-decorated defective carbon paper as a self-supported catalyst for oxygen electrocatalysis and rechargeable zinc-air battery

Carbon-supported transition-metal materials have been recognized as efficient bifunctional electrocatalysts for oxygen evolution/reduction reactions (OER/ORR) in rechargeable zinc-air batteries. While the pursuit of high-performance catalysts remains critical, the industrial applications of catalysts and their synthesis methods cannot be ignored. In this work, a self-supported hybrid catalyst is prepared by anchoring cobalt oxide particles on defective carbon papers. Commercial carbon papers were first treated by nitrogen plasma to introduce surface defects and increase their surface hydrophilicity, thereby facilitating the subsequent cobalt deposition. The resulting catalyst with abundant carbon defects and deposited Co oxide particles exhibits an increased number of active sites and improved surface conductivity compared to pristine carbon papers, leading to enhanced bifunctional electrocatalytic performance. When employed in a liquid zinc-air battery, this catalyst shows acceptable discharging and charging potentials, along with a higher durability than the battery utilizing a mixed noble metal-based catalyst. Our findings represent a novel and large-scale application strategy for synthesizing self-supported carbon-supported transition-metal materials for rechargeable zinc-air batteries and associated energy storage systems.

Harnessing the Synergistic Effects of Ir Co-Decorated NiMn-LDH: a Multi-Analytical Approach to Boost Electrocatalytic Overall Water Splitting Activity in Alkaline Condition

Fine control over the Ir precursor to the Nickel-based layered double hydroxides (LDHs) is significant for decorating both single atoms (SA) and nanoclusters (NC), thus modulating catalytic kinetics and improving overall performance. In this study, NiMn-LDH is synthesized and co-decorated it with Iridium, introducing a new pathway for developing efficient bifunctional electrocatalysts in water-splitting technologies. Additionally, a typical fibrous material has developed by immobilizing.I r SA - I r N C 12 - NiMn - LDH ${\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{SA}}}} - {\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{N}}{{{\mathrm{C}}}_{12}}}} - {\mathrm{NiMn}} - {\mathrm{LDH}}$ onto PAN (polyacrylonitrile) nanofibers (I r SA - I r N C 12 - NiMn - LDH - F ${\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{SA}}}} - {\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{N}}{{{\mathrm{C}}}_{12}}}} - {\mathrm{NiMn}} - {\mathrm{LDH}} - {\mathrm{F}}$ ) using a feasible electrospinning technique. Notably, the catalyst exhibits low overpotentials of 249 and 110 mV for oxygen (OER) and hydrogen evolution reactions (HER) at 10 mA cm- 2, and a low cell voltage of 1.65 V for total water splitting (TWS). Additionally,I r SA - I r N C 12 - NiMn - LDH - F ${\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{SA}}}} - {\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{N}}{{{\mathrm{C}}}_{12}}}} - {\mathrm{NiMn}} - {\mathrm{LDH}} - {\mathrm{F}}$ remained stable and effective in alkaline OER, HER, and TWS for over 50 h. Furthermore, X-ray adsorption near-edge spectrum (XANES) experiments, together with theoretical calculations, show that the synergistic effect of IrSA andI r N C 12 ${\mathrm{I}}{{{\mathrm{r}}}^{{\mathrm{N}}{{{\mathrm{C}}}_{12}}}}$ which helps to enhance the catalytic activity, promoting electron rearrangement and lowering the reaction energy barrier.

Three-Dimensional Network of Highly Uniform Cobalt Oxide Microspheres/MXene Composite as a High-Performance Electrocatalyst in Hydrogen Evolution Reaction

Due to its affordable cost, excellent redox capability, and relatively effective resistance to corrosion in alkaline environments, spinel Co3O4 demonstrates potential as a viable alternative to noble-metal-based electrocatalysts. Nevertheless, these materials continue to exhibit drawbacks, such as limited active surface area and inadequate intrinsic conductivity. Researchers have been trying to increase the electrical conductivity of Co3O4 nanostructures by integrating them with various conductive substrates due to the low conductivity of pristine Co3O4. In this study, uniform cobalt glycerate solid spheres are first synthesized as the precursor and subsequently transformed into cobalt oxide microspheres by a simple annealing procedure. Co3O4 grown on the surface of Ti3C2Tx-MXene nanosheets (Co3O4/MXene) was successfully synthesized through electrostatic attraction. In order to create a positively charged surface, the Co3O4 microspheres were treated with aminopropyltriethoxysilane. The Co3O4/MXene exhibited a low overpotential of 118 mV at 10 mA cm-2 and a Tafel slope of 113 mV dec-1 for the hydrogen evolution reaction, which is much lower than the pristine Co3O4 at 232 and 195.3 mV dec-1.