Study On The Novel Electrocatalysts For Carbon Dioxide Reduction And Hydrogen Evolution Reaction

The ever-increasing consumption of fossil fuels has accelerated the depletion ofnatural resources and led to overproduction of carbon dioxide as greenhouse gas. In the pastdecades, different technologies have been proposed to reduce the emission of CO2. Amongthese technologies, conversion of CO2into useful low-carbon fuels, such as CO, CH4,HCOOH, CH3OH, represents an attracting technology because that it offers a potential wayto recycle CO2into valuable products for energy needs or for industrial applications. Inparticular, the electrochemical reduction of CO2has drawn extensive attention, as thereaction proceeds cleanly by utilizing sustainable energy (such as wind, hydro and solar).Unfortunately, this avenue is greatly inhibited by the lack of efficient catalysts, whichshould ideally possess sufficiently low overpotentials and high current densities to achievehigh energetic efficiency. Therefore, exploring new electrocatalysts that efficiently reduceCO2into liquid fuels, especially in mild conditions, is extremely important.Herein, we report the preparation of monodisperse Cu-Pt nanoparticles (NCs) by usinga co-reduction strategy. With this synthetic method, uniformly distribution of NCs can berealized and atom ratio of Pt and Cu can be concisely controlled. Correspondingly, theCu-Pt NCs samples show compositional dependent activity towards electrochemicalreduction of CO2. We discover that among all the samples as efficient electrocatalysts forCO2reduction in0.5M KHCO3at room temperature, the sample of Cu-Pt (3:1) NCsexhibited the best performance for CO2reduction, i.e. the lowest onset potential (ca.-0.972V) and highest CO2reduction current density (ca.0.598mA cm-2at-1.3V vs. SCE). Basedon the analysis, we present a plausible mechanism to understand the compositionaldependent activity of Cu-Pt NCs.On the other hand, hydrogen (H2), as an efficient energy carrier and clean energyresource, has been vigorously pursued to resolve the global issues of severe energy shortageand environmental deterioration. In particular, sustainable hydrogen production with watersplitting technology by using renewable energy in the form of electricity is considered as apractical way. However, an advanced hydrogen evolution reaction (HER) electrocatalyst isthe central to the development of effective water splitting technology. In this work, wedescribe the preparation of flexible three-dimensional and durable electrode composed ofMoS2nanoparticles grown on bacteria-cellulose-derived carbon fibers foam (MoS2/CNFs).The MoS2/CNFs foam was used as a bulky and flexible HER electrocatalyst, exhibiting excellent catalytic activity for a hydrogen evolution reaction in an acidic electrolyte (16mAcm-2at overpotential of230mV). Further, this novel HER electrocatalyst shows a low onsetoverpotential of120mV, a small Tafel slope of44mV dec-1, a high exchange currentdensity of0.09mA cm-2, and a Faradaic efficiency of nearly100%. This work offers anattractive strategy of preparing bulky and flexible electrocatalyst for large-scale watersplitting technology.