Preparation And Electrocatalytic Performance Of Transition Metal Hydroxide Hollow Nanocubes

The electrolysis of water has been considered as a promising way for the production of hydrogen and oxygen.However,with sluggish kinetics due to the multistep proton-coupled electron transfer,oxygen evolution reaction?OER?is always more challenging and thermodynamically and kinetically demanding.Currently,the most active OER catalysts are the noble metal oxides?RuO₂ and IrO₂?,but the high cost and scarcity of such catalysts have impeded their scale-up applications in energy conversion systems.Therefore,cost-effective and earth-abundant catalysts as possible alternatives to Ru/Ir-based compounds for OER are highly desired.Through the study of OER catalysts,it can be found that transition metal hydroxides always used as OER catalysts,because transition metal hydroxides are cost-effective and well as OER catalysts.Hollow materials have received a great deal of attention because they can expose more catalytically active sites to achieve excellent performance.Recently,a hollow transition metal hydroxide was prepared using a transition metal oxide as a sacrificial template,such as Cu₂O nanocubes.This efficient method can control the morphology and size of the target product by adjusting the morphology and that of the template.Considering the above factors,transition metal hydroxides prepared by Cu₂O cube templates.To investigate the effect of catalyst size on its catalytic performance,different size?50 nm,500 nm?Cu₂O cubes were used as sacrificial templates to prepare different size transition metal?Fe,Co,Ni?hydroxides.Catalytically decompose water evolution oxygen and compare the effect of size on the catalyst.With Cu₂O nanocubes of different sizes,hollow M?OH?_x?M = Fe,Co,Ni?cubic structures are obtained.It turned out that hydroxides have the same structure with Cu₂O.Their electrocatalytic activity towards OER is systematically compared.It suggests that size of the catalysts has a huge impact on their OER electrocatalytic activity.Generally,the double metal hydroxide catalyst has better catalytic performance than the single metal hydroxide catalyst.We also synthesize NiFe?OH?_x,NiMn?OH?_x and NiCo?OH?_x using the 50 nm Cu₂O cube as the sacrificial template.A comparative study of the electrocatalytic oxygen evolution reaction?OER?of the three double metal hydroxide nanocubes with similar size reveals that NiFe?OH?_x has better activity in terms of overpotential.