Controllable Preparation Of Nickel-based Nanomaterials And Applications In Energy And Photoelectric Conversion

In the past half century,rapid growth of population,urbanization and living standards have rapidly increased global energy consumption and environmental burdens.In the next few years,energy consumption and environmental pollution will continue to grow substantially.It is extremely urgent to seek new technologies to provide new energy sources such as hydrogen and solar energy,as well as a clean environment to human beings.Due to its large specific surface area,strong mechanical properties(such as strength and toughness),unique properties in terms of light,electricity,magnetism and thermal,nanomaterials have been widely investigated by researchers all over the world.Among them,nickel-based nanomaterials stand out in many nanomaterials due to their abundant resources,low cost and high reactivity.Therefore,based on the unique properties and wide applications of nickel-based nanomaterials,our recent works discuss in detail the applications of nickel-based nanomaterials in photoelectrocatalysis,perovskite solar cells,and lithium-ion batteries.The research contents are as following:(1)Controllable preparation of two-dimensional Ni-TiO2 nanosheets and their applications in photoelectrocatalysis.Sol-gel method is developed to synthesize the two-dimensional Ni-TiO2 nanosheets.The structure and morphology of the samples were characterized by XRD,XPS,TEM,SEM and other testing methods.When it acts as a photocatalyst for the oxygen evolution reaction,it exhibits high catalytic activity and photosensitivity.At a voltage of 1.7 V,the current density of the samples is 20.05 mA cm-2,which is about 2.25 times larger than that without light.On the kinetics of OER,Ni-TiO2 exhibits a Tafel slope of 139 mVdec-1 in the dark.Importantly,with AM 1.5G irradiation;The Tafel slope is descreased significantiy to 91 mV dec-1.The proposed Ni-TiO2 nanosheet structure provides a new way for high-performance photoelectrocatalysis.(2)Study on the performance enhancement of the Ni-TiO2 in perovskite solar cells.The optimal amount for effectively improving the photoelectric conversion efficiency of the perovskite solar cell is 0.3 wt%Ni-TiO2(0.05).The supported Ni metal can indeed improve the transport of the electrons and achieve effective electron transfer.With AM 1.5G irradiation,the introduced Ni-TiO2 layer can effectively improve the photoelectric conversion efficiency from 8.73%to 10.72%.Our work provides an effective way to improve electron transfer and achieve efficient photoelectric conversion efficiency.(3)Improved cycling stability of NiS2 cathodes within LIBs through designing a "kiwano"hollow structure.The unique "kiwano-like" NiS2 hollow structures have been synthesized via hydrothermal method.When tested as a cathode for LIBs,the NiS2 electrode delivers the excellent specific capacity of 681 mAh/g even after 100 cycles.Even after 400 cycles at 0.2 C,a high reversible capacity of 580.6 mAh/g was maintained.It is worth noting that only a single intermediate product,i.e.Ni3S4,is formed,rather than other nickel sulphides,which is observed within the in situ TEM observations.The material shows good cycling stability.The proposed "kiwano"structure concept will provide a practical strategy for enhancing cycling life of electrode materials.