Preparation Of FeNb(Mo)B Amorphous Nanostructures And Their Electrocatalytic Activities For Hydrogen Evolution Reaction

Long-term stability is a key problem for commonly used high-activity hydrogen evolution catalysts witch are mostly crystalline powders.Finding high-stability electrolyzed catalysts with highly activity and low cost the essential to solving the hydrogen energy problem.Studies have shown that Amorphous strips exhibit excellent catalytic performance and stability,and also exhibit high strength and corrosion resistance due to their unique structure.However,it is difficult to obtain an amorphous three-dimensional structure to further increase the catalytic performance.In this experiment,a three-dimensional amorphous nanostructure was obtained by de-alloying?-Fe nanocrystal/amorphous biphasic.Firstly,a strip of Fe₈₂Nb₆B₁₂?Fe₈₂-?Nb?Mo?₆-B₁₂2 and Fe₈₂Mo₆B₁₂2 was prepared by using a vacuum melting furnace and melt-spinning,and then moved into 0.5 mol/L sulfuric acid for amorphous nanostructure by de-alloying.The?-Fe nanocrystalline/amorphous duplex alloy was successfully obtained by adjusting the composition of the Fe₈₂Nb₆B₁₂ at a speed of 2?3 krpm.The content and size of the?-Fe nanocrystals increase as the revolutions decreases.The de-alloying process is mainly the selective dissolution of?-Fe nanocrystals.The strong corrosion resistance of Fe-Nb-B amorphous matrix and the existence of Nb passivation film ensure that the amorphous Fe-Nb-B skeleton survives during the de-alloying process,thus obtaining an amorphous porous structure.The 2 krpm sample had the largest specific surface area after de-alloying,and exhibits the best hydrogen evolution performance.To reaches current density of 10 mA cm^-2,requires overpotential of 220 mV in 0.5 mol/L H₂SO₄.Alloy composition has a significant effect on the morphology of the strip after de-alloying.The?-Fe nanocrystal is still the main crystallized phase of Fe-Nb-Mo-B.And a small amount of Fe-B compound appears in the 2 krpm sample.However,the morphology of Fe₈₂Nb₃Mo₃B₁₂ and Fe₈₂Nb₁Mo₅B₁₂ samples after de-alloying is quite different.An amorphous porous structure containing Mo element was obtained for the Fe₈₂Nb₃Mo₃B₁₂ 2⁵krpm samples after de-alloying,while an amorphous iron oxide nanosheet array was obtained for the Fe₈₂Nb₁Mo₅B₁₂ 2⁵ krpm samples under the same condition.It is found that 3%Mo element substitution increases the corrosion resistance of the amorphous matrix,which makes the Fe₈₂Nb₃Mo₃B₁₂ amorphous skeleton stable in the de-alloying process,while 5%Mo element replacement reduces the corrosion resistance of the amorphous matrix,Fe₈₂Nb₁Mo₅B₁₂ It is difficult for the matrix to maintain an amorphous state during the de-alloying process,and thus an amorphous porous structure cannot be obtained.In order to further study the growth and hydrogen evolution properties of amorphous nanosheets,we completely replaced the Nb element with Mo.The precursor strip of Fe₈₂Mo₆B₁₂ still mainly precipitated?-Fe nanocrystals,and other phases such as Fe-B appeared in samples prepared under 1,2 krpm,and?-Fe nanocrystalline/amorphous duplex alloys were successfully obtained at 3⁵ krpm.For 1?2 krpm samples,the corrosion process of the sample reacted violently,and the surface formed a porous structure after corrosion.Amorphous iron oxide nanosheets were successfully obtained for 3⁵ krpm samples after alloying.The thickness of the nanosheet is related to the de-alloying time and the content of?-Fe.After 1 h of de-alloying,the thickness of the nanosheet can reach 2?m for the 3 krpm sample.The de-alloying process and corrosion performance of the strips show that the Fe-Mo-B amorphous matrix has poor corrosion resistance,and the amorphous matrix and?-Fe are simultaneously corroded during the de-alloying process.The migration of Fe element during the corrosion of the surface layer is an important reason for the growth of nanosheets.The 3 krpm sample has the largest specific surface area after da-alloying,and exhibits the best hydrogen evolution performance.It only requires overpotential of 148 mV to drive 10mA/cm² in 0.5 mol/L H₂SO₄,and The Tafel slope is 93 mV/dec.and it exhibits excellent self-stability.