Preparation And Research Of Hierarchical Porous Water Decomposition Catalytic Material

As a renewable,clean and efficient energy,hydrogen energy attracts considerable interest due to the growing energy and ecological crisis.Water spitting is a fast and pollution-free method to produce hydrogen.However,the high overpotentials for both hydrogen revolution reaction（HER）and oxygen revolution reaction（OER）make water splitting high-energy consuming and demand the application of efficient catalysts.In alkaline water spitting,Ni-based catalysts with low cost can be used.Nevertheless,the commercial Ni catalysts exhibit much lower activity and stability compared with the Pt and Ru-based catalysts.With the aim of further improving the catalytic activity and stability of the Ni-based catalysts,this research focuses on developing new catalysts by forming hierarchical porous structure and alloying.Firstly,ternary Ni-Fe-Cu coatings were prepared by dynamic hydrogen bubble template method（DHBT）co-deposition.The influence of additives,plating solutions and rapid CV treatment on the composition,morphology and catalytic performance of the Ni-Fe-Cu coatings were investigated.The results showed that the alloy with a composition of Ni₂₁Fe₁₀Cu₆₉ had the best HER activity.The HER over-potential at 10 m A/cm²(η-₁₀)was 78 m V,and the Tafel slope was 96 m V/dec.The outstanding catalytic activity was attributed to the high electrochemical active area of the catalyst provided by the hierarchical porous structure.After a rapid CV treatment,a layer of single-crystalline metal oxides was epitaxially grown on the ternary Ni-Fe-Cu alloy,resulting in a metal-metal oxide core-shell structure.The Ni₄₆Fe₂₀Cu₃₄ subjected to the CV treatment had the best OER activity.The OER over-potential at 10 m A/cm²(η₁₀)is246 m V,and the Tafel slope was 46 m V/dec.Moreover,it showed outstanding durability towards OER stability test,i.e.,the catalytic activity kept stable（>99%）after catalyzing at 10m A/cm² and 300 m A/cm² for 10 hours.Secondly,hexanary Ni-Fe-Cu-Co-Mo-Pt coatings with hierarchical porous structures were prepared by DHBT co-deposition.The EDX mapping proved that the six elements were homogenously dispersed in the coatings.By tuning the plating solutions and deposition parameters,the alloy with a composition of Ni₂₀Fe₁₆Cu₁₇Co₂₀Mo₁₂Pt₁₅ had been obtained,which displayed the best HER and OER catalytic activity.η-₁₀ andη₁₀ are 36 m V and 278 m V,respectively,and the Tafel slope are 68 m V/dec and 41 m V/dec,respectively.Moreover,after a stability test at 500 m A/cm² for more than 10 hours.The catalytic activity towards both HER and OER kept stable（>99%）.Finally,hexanary Ni-Fe-Cu-Co-Mo-W coatings with a hierarchical porous structure were prepared by DHBT co-deposition.When compared with hexanary Ni-Fe-Cu-Co-Mo-Pt coating,the W-bearing catalysts had higher OER catalytic activity.The Ni₂₃Fe₁₈Cu₂₂Co₁₆Mo₁₅W₆display a smallη₁₀ of 250 m V,and a Tafel slope of 46 m V/dec.Moreover,it showed outstanding durability towards OER stability test at 500 m A/cm² over 10 hours.