Self-supported CoMoS4 nanosheet array as an efficient catalyst for hydrogen evolution reaction at neutral pH

Development of earth-abundant electrocatalysts, particularly for high-efficiency hydrogen evolution reaction （HER） under benign conditions, is highly desired, but still remains a serious challenge. Herein, we report a high-performance amorphous CoMoS4 nanosheet array on carbon cloth （CoMoS4 NS/CC）, prepared by hydrothermal treatment of a Co（OH）F nanosheet array on a carbon cloth （Co（OH）F NS/CC） in （NH4）2MoS4 solution. As a three-dimensional HER electrode, CoMoS4 NS/CC exhibits remarkable activity in 1.0 M phosphate buffer saline （pH 7）, only requiring an overpotential of 183 mV to drive a geometrical current density of 10 mA·cm-2. This overpotential is 140 mV lower than that for Co（OH）F NS/CC. Notably, this electrode also shows outstanding electrochemical durability and nearly 100% Faradaic efficiency. Density functional theory calculations suggest that CoMoS4 has a more favorable hydrogen adsorption free energy than Co（OH）F.

Sulfur-induced dynamic reconstruction of iron-nitrogen species for highly active neutral oxygen reduction reactions

The neutral oxygen reduction reaction(ORR)has attracted tremendous attention for its broad prospects in next-generation power storage systems.However,the extremely sluggish cathodic reaction process and the limited cognition of the reaction mechanism greatly hinder its practical application.Here,we demonstrate a dynamic reconstruction behavior induced by sulfur of the iron-nitrogen(Fe-Nx)species in neutral solution.Our developed FeS_(1)N_(3)-OH configuration effectively optimizes the reaction kinetics by regulating the adsorption energy of oxygen intermediates for central catalytic sites.Consequently,this structure exhibits over 363%enhancement in ORR mass activity compared to the pristine FeN_(4) sites under neutral electrolyte.Moreover,a neutral zinc-air battery assembled with this electrocatalyst reached an ultrahigh peak power density(81.2 mW cm^(−2)),robust stability(more than 100 h)as well as superior tolerance to extreme environments(operating between−20°C and 60°C),representing a critical breakthrough for neutral ORR exploration and application.

Motivating Ru-bri site of RuO_(2)by boron doping toward high performance acidic and neutral oxygen evolution

The electrocatalysis of oxygen evolution reaction(OER)plays a key role in clean energy storage and transfer.Nonetheless,the sluggish kinetics and poor durability under acidic and neutral conditions severely hinder practical applications such as electrolyzer compatible with the powerful proton exchange membrane and biohybrid fuel production.Here,we report a borondoped ruthenium dioxide electrocatalyst(B-RuO_(2))fabricated by a facile boric acid assisted strategy which demonstrates excellent acidic and neutral OER performances.Density functional theory calculations and advanced characterizations reveal that the boron species form an anomalous B–O covalent bonding with the oxygen atoms of RuO_(2)and expose the fully coordinately bridge ruthenium site(Ru-bri site),which seems like a switch that turns on the inactive Ru-bri site into OER-active,resulting in more exposed active sites,modified electronic structure,and optimized binding energy of intermediates.Thus,the B-RuO_(2)exhibits an ultralow overpotential of 200 mV at 10 mA/cm^(2)and maintains excellent stability compared to commercial RuO_(2)in 0.5 M sulfuric acid.Moreover,the superior performance is as well displayed in neutral electrolyte,surpassing most previously reported catalysts.