The Research On Preparation And Hydrogen Evolution Reaction Properties Of Nanoporous Transition Metal Sulfide

The use of transition metal compound materials instead of noble metals as catalysts has broad prospects for achieving practical hydrogen production from water splitting.Developing low-cost,efficient,and durable HER catalysts remains a huge challenge.Based on the strategy for improving the HER performance of electrocatalyst,a series of research is carried out around increasing the density of active sites or/and enhance the intrinsic activity of each active site.1.The aluminum-rich transition metal alloy ribbon Ni_1.7Co_3.3Al₉₅ was prepared by rapid solidification technology,and the nanoporous solid solution Ni_0.33Co_0.67 was obtained by subsequent dealloying?de-alumination?treatment.Finally,CVD technology was used to dope non-metal atoms S into nanoporous Ni_0.33Co_0.67 and successfully obtained a bimetallic pyrite-type compound Ni_0.33Co_0.67S₂ with inherited porous network structure.The HER performance tests show that Ni_0.33Co_0.67S₂ has improved catalytic activity.Specifically,the required overpotential at current densities of 10 mA cm^-22 and Tafel slope are only 191.2 mV,and 93.64 mV dec^-1,respectively.Which are lower than NiS₂(199.0 mV and 118.41 mV dec^-1,respectively.)and CoS₂(201.8 mV and 108.17 mV dec^-1,respectively.)prepared under the same conditions.In addition,the long-term stability test shows that Ni_0.33Co_0.67S₂ has good durability.Further analysis shows that the performance improvement of Ni_0.33Co_0.67S₂ is due to the good charge transfer ability brought by the bimetal and the increased electrochemical active specific surface area given by the porous precursor and S doping.2.A porous network heterostructure catalyst NiS/MoS₂ was prepared by a similar method.The HER performance tests show that NiS/MoS₂ has improved HER catalytic activity.Specifically,the overpotential required to deliver a current density of 10 mA cm^-22 and the Tafel slope are only 186.3 mV and 103.6 mV dec^-1,respectively.Which are lower than the MoS₂(228.0 mV and 136.6 mV dec^-1,respectively.)prepared under the same conditions and precursor np-NiMo(225.8 mV and 105.4 mV dec^-1,respectively.).In addition,the long-term stability test shows that NiS/MoS₂ has good durability.Further analysis shows that the enhanced HER performance is attributed to the improvement of specific surface area and many heterogeneous interface defect sites brought about by the porous network structure and the abundant nanosheets generated on the framework.3.A bi-non-metal-doped porous network transition metal catalyst P-NiS₂ was prepared by a similar method.Compared with pure NiS₂,P-NiS₂ exhibits improved HER performance.The required overpotential at current densities of 10 mA cm^-2 is only 196.0mV,which is lower than NiS₂?221.0 mV?.Besides,the Tafel slope is only 110.4 mV dec^-1,which is also lower than NiS₂(111.3 mV dec^-1).In addition,the long-term stability test shows that P-NiS₂ has good durability.This is mainly due to the electronic structure regulation effect of P atoms on the surface metal atoms of NiS₂,which makes the binding energy of the catalyst material to the reaction intermediate more moderate.In addition,the rich intertwined nanoneedle flake structure contributes many reaction sites for HER.The above attempts to improve the performance of water splitting catalysts have proposed new design ideas and experimental foundations for the development of low-cost,efficient,and durable HER catalyst materials.