Recent progress on earth abundant electrocatalysts for hydrogen evolution reaction(HER) in alkaline medium to achieve efficient water splitting–A review

Developing earth-abundant-electrocatalysts for hydrogen evolution reaction is one of the promising ways to achieve efficient water-splitting for hydrogen production(a clean chemical fuel).This paper reviews the activity,stability and durability for hydrogen evolution reaction in alkaline medium of different types of recently reported potential electrocatalysts such as Ni,Co,NiCo,Fe,Cu,W,Mo,Se,Mn.Zn,V,and metal free based earth-abundant-electrocatalysts.Further,this paper reviews the strategies used to achieve the remarkably low overpotential(including r/i0:<35mV),high long term stability(including^:100 h)and high durability(including>5000 cycles)of potential earth-abundant-electrocatalysts for hydrogen evolution reaction in alkaline medium and those are better or well comparable with the state-of-the-art,noble,Pt/C electrocatalyst.Finally,this paper summarizes the efficient strategies such as preparing porous structured materials,preparing nanostructured materials with superaerophobic surface,preparing nanostructured materials,preparing carbon composites/integrating electrocatalysts with carbon,preparing amorphous materials,preparing materials w让h oxygen vacancies/defects,preparing metal chalcogenides,preparing bimetallic/multi-metallic materials,doping metals or heteroatoms,preparing electrocatalysts with core-shell structure,decorating electrocatalysts with amines,preparing homojunction/heterojunction structured materials,preparing hollow structured materials,and preparing boronrich surface to enhance the activity,stability,and durability for HER.

Recent advances on flexible electrodes for Na-ion batteries and Li–S batteries

Flexible energy storage devices are essential for emerging flexible electronics. The existing state-of-the-art Li-ion batteries are slowly reaching their limitation in terms of cost and energy density. Hence, flexible Na-ion batteries (SIBs) with abundanee Na resources and Li-S batteries with high energy density become the alternative for the Li-ion batteries in future. This review summarizes the recent advances in the development of flexible electrode materials for SIBs with metallic matrix and carb on aceous matrix such as carb on nano-tubes, carbon nano-fiber, graphene, carbon cloth, carbon fiber cloth, and cotton textiles. Then, the potential prototype flexible full SIBs are discussed. Further, the recent progress in the development of flexible electrode materials for Li-S batteries based on carb on nano-fiber, carb on nano-tubes, graphene, and cotton textiles is reviewed. Moreover, the design strategies of suitable interlayer, separator, electrolyte, and electrodes to prevent the dissolution and shuttle effect of polysulfides in flexible Li-S batteries are provided. Finally some prospective investigation trends towards future research of flexible SIBs and Li-S batteries are also proposed and discussed. The scientific and engineering knowledge gained on flexible SIBs and Li-S batteries provides conceivable development for practical application in near future.