| Global environmental issues associated with climatic changes induced by greenhouse gases are dramatic concerns of today's energy-conscious society.The ever-increasing world population and its increasing affluence with associated higher energy consumption put huge pressure for expanding our current energy infrastructure,which has been,and still is,heavily relying on limited and environmentally unfriendly sources,such as coal,oil and gas.The increasing atmospheric pollution,global warming,depletion of fossil-fuels and lack of energy security,represent the most important imperatives to be urgently addressed for a sustainable future.Both the hydrogen evolution reaction?HER?and the dye sensitized solar cells?DSSCs?are considered to have the potential to solve the energy crisis and environmental pollution.However,all these ways rely on the availability of noble materials and systems capable of exploiting their full possibilities to the grand energy challenge.So the first challenge to face is to solve the consumption of noble materials.one available way is to disperse the pure metal with a good carrier,such as silicon nanowires?SiNWs?.SiNWs have recently attracted a lot of attentions for their appealing properties:large surface-area-to-volume ratio,non-toxic,biocompatible and earth-abundant.In addition,the numerous Si-H bonds,which,existing on HF-etched SiNWs,can easily reduce metal ions and firmly anchor the in-situ grown metal nanoparticles.Therefore,this paper mainly introduces the effect of the combination of SiNWs and noble metal on HER and DSSC.The main results of this dissertation are listed as follow:?1?Amorphous rhenium nanoparticles modified silicon nanowires were prepared via reducing Re ion by Si-H bonds,which were employed to electrocatalysize the hydrogen evolution reaction because amorphous structure may have excellent catalytic activity.It is interesting that an obvious self-activation for Re/Si NW catalysts was observed with the apparent current density enhanced by 11 times its previous value after a 3,000 s of continuous cyclic voltammetry scanning,and the catalytic performance remained steady thereafter.The optimal electrocatalytic performance was found with the Re:Si mass ratio of 31.1:68.9,resulting in a Tafel slope of 81 mV·dec-1and overpotential of 100 mV to get a current density of 10 mA·cm-2.?2?In order to further study the effect of SiNW on HER,we have prepared Au/SiNW catalyst for HER.The results once again verified the synergistic effect of the SiNW and the noble metal in the electrocatalytic hydrogen evolution reaction.The current density of pure Au nanoparticles is much lower than those of Au/SiNW electrocatalysts because of the easy agglomeration of pure Au nanoparticles in the HER process.?3?We introduce the earth-abundant silicon and combine it with Pt nanoparticles as the counter electrode in dye-sensitized solar cells to enlarge surface area and enhance the activity of Pt.Si-H bonds can reduce metal ions and enable small metal nanoparticles grown on the surface of silicon nanowires,which can effectively prevent metal nanoparticles from agglomeration in the catalysis.The density functional theory?DFT?calculation shows that the adsorption energy of I atom on the Pt/Si interface is-0.8 eV,which is the optimal adsorption energy for triiodide reduction,indicating that Pt/Si is a perfect material for the counter electrode.The electrochemical characterizations and the photocurrent-voltage performance experimentally confirm that Pt/SiNW is a better counter electrode material than other metal/Si NW composites and Pt,which is in accordance with DFT calculations.The power conversion efficiency of device based on the Pt/SiNW electrode is 3.8%higher than that of the device based on Pt. |
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