Anchoring γ-MnO2 within β-NiCo(OH)2 as an Interfacial Electrode Material for Boosting Power Density in an Asymmetric Supercapacitor Device and for Oxygen Evolution Catalysis

Recent Trends and Perspectives in Single-Entity Electrochemistry: A Review with Focus on a Water Splitting Reaction

Electrochemical measurements involving single nanoparticles have attracted considerable research attention. In recent years, various studies have been conducted on single-entity electrochemistry (SEE) for the in-depth analyses of catalytic reactions. Although, several electrocatalysts have been developed for H2 energy production, designing innovative electrocatalysts for this purpose remains a challenging task. Stochastic collision electrochemistry is gaining increased attention because it has led to new findings in the SEE field. Importantly, it facilitates establishing structure activity relationships for electrocatalysts by monitoring transient signals. This article reviews the recent achievements related to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) using different electrocatalysts at the nanoscale level. In particular, it discusses the electrocatalytic activities of noble metal nanoparticles, including Ag, Au, Pt, and Pd nanoparticles, at the single-particle level. Because heterogeneity is a key factor affecting the catalytic activity of nanostructures, our work focuses on the influence of heterogeneities in catalytic materials on the OER and HER activities. These results may help to achieve a better understanding of the fundamental processes involved in the water splitting reaction.

Ni-Co-Mn hydrotalcite-derived hierarchically porous sulfide for hybrid supercapacitors

Ternary transition metal sulfides have attracted much attention due to their superior electrochemical properties. Nevertheless, it is difficult to commercialize sulfides due to their intrinsic properties such as dull reaction kinetics and an insufficient number of active sites. Herein, a self-supporting porous NiCoMnS sulfide (NiCoMnS/NF) arrayed on nickel foam (NF) with 3D honeycomb-like structure was designed and prepared via a hydrothermal and post-sulfidation process. It was found that the 3D hierarchically network architecture, constructed by nanosheets with abundant cavities, endowed NiCoMnS/NF with a high specific area and rich ion/electron-transport channels, which facilitated ion/electron transfer and Faradaic reaction kinetic. The optimal NiCoMnS/NF exhibited a markedly improved electrochemical performance due to the merits of complementary multi-composition and unique 3D network structure with multi-level "superhighways". Furthermore, the NiCoMnS//AC device fabricated with NiCoMnS/NF cathode and activated carbon (AC) anode delivered an excellent specific charge and exceptional energy density. This work offers a reference for designing the structure of electrode materials.

Waste Adsorbent-Derived Interconnected Hierarchical Attapulgite@Carbon/NiCo Layered Double Hydroxide Nanocomposites for Advanced Supercapacitors

The attapulgite@carbon/NiCo layered double hydroxide nanocomposites based on waste adsorbents are manufactured via simple and eco-friendly calcination and hydrothermal methods, by which they would be considerable electrode materials for advanced supercapacitors. To achieve sustainable development, the spent tetracycline-loaded attapulgite can act as a cost-effective available carbon source as well as a matrix material for carbon species and NiCo layered double hydroxide simultaneously. A controlled amount of attapulgite@carbon could be used to regulate the electrochemical properties of nanocomposites. The generated electrodes possess superior electrochemical properties with a specific capacitance of 2013.8 F g^-1 at 0.5 A g^-1, a retention rate of 87.7% at 5 A g^-1, and a cyclic stability of 64.9% for 4000 cycles at 5 A g^-1. Thus, the asymmetric supercapacitor device assembled with attapulgite@carbon/NiCo layered double hydroxide nanocomposites||active carbon shows a maximum capacitance of 231.3 F g^-1 at 0.5 A g^-1, with a preeminent energy density of 82.2 Wh kg^-1 when its power density is 4318 W kg^-1. This approach would contribute to the development of supercapacitors in an efficient and effective manner, as well as provide a feasible strategy for solving tetracycline pollution and recycling waste adsorbents to achieve sustainable development.