Highly Sensitive Hydrazine Sensor Based on Co(OH)2Nanoflakes Electrochemically Deposited on MWCNTs

Graphene/MoS2/FeCoNi(OH)x and Graphene/MoS2/FeCoNiPx multilayer-stacked vertical nanosheets on carbon fibers for highly efficient overall water splitting

Development of excellent and cheap electrocatalysts for water electrolysis is of great significance for application of hydrogen energy. Here, we show a highly efficient and stable oxygen evolution reaction (OER) catalyst with multilayer-stacked hybrid structure, in which vertical graphene nanosheets (VGSs), MoS₂ nanosheets, and layered FeCoNi hydroxides (FeCoNi(OH)_x) are successively grown on carbon fibers (CF/VGSs/MoS₂/FeCoNi(OH)_x). The catalyst exhibits excellent OER performance with a low overpotential of 225 and 241 mV to attain 500 and 1000 mA cm^-2 and small Tafel slope of 29.2 mV dec^-1. Theoretical calculation indicates that compositing of FeCoNi(OH)_x with MoS₂ could generate favorable electronic structure and decrease the OER overpotential, promoting the electrocatalytic activity. An alkaline water electrolyzer is established using CF/VGSs/MoS₂/FeCoNi(OH)_x anode for overall water splitting, which generates a current density of 100 mA cm^-2 at 1.59 V with excellent stability over 100 h. Our highly efficient catalysts have great prospect for water electrolysis.

Three-dimensional interconnected Co(OH)2 nanosheets on Ti mesh as a highly sensitive electrochemical sensor for hydrazine detection

Three-dimensional interconnected Co(OH)₂ nanosheets on TM, prepared by low cost and simple electrodeposition method, exhibit highly sensitive electrochemical hydrazine detection.

Two-Dimensional MoS2 Confined Co(OH)2 Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes

The development of abundant and cheap electrocatalysts for the hydrogen evolution reaction (HER) has attracted increasing attention over recent years. However, to achieve low-cost HER electrocatalysis, especially in alkaline media, is still a big challenge due to the sluggish water dissociation kinetics as well as the poor long-term stability of catalysts. In this paper we report the design and synthesis of a two-dimensional (2D) MoS₂ confined Co(OH)₂ nanoparticle electrocatalyst, which accelerates water dissociation and exhibits good durability in alkaline solutions, leading to significant improvement in HER performance. A two-step method was used to synthesize the electrocatalyst, starting with the lithium intercalation of exfoliated MoS₂ nanosheets followed by Co²⁺ exchange in alkaline media to form MoS₂ intercalated with Co(OH)₂ nanoparticles (denoted Co-Ex-MoS₂), which was fully characterized by spectroscopic studies. Electrochemical tests indicated that the electrocatalyst exhibits superior HER activity and excellent stability, with an onset overpotential and Tafel slope as low as 15 mV and 53 mV dec^-1, respectively, which are among the best values reported so far for the Pt-free HER in alkaline media. Furthermore, density functional theory calculations show that the cojoint roles of Co(OH)₂ nanoparticles and MoS₂ nanosheets result in the excellent activity of the Co-Ex-MoS₂ electrocatalyst, and the good stability is attributed to the confinement of the Co(OH)₂ nanoparticles. This work provides an imporant strategy for designing HER electrocatalysts in alkaline solutions, and can, in principle, be expanded to other materials besides the Co(OH)₂ and MoS₂ used here.