Abstract
Cu-based materials are commonly used in electrocatalytic nitrate reduction reactions(NO3RR).NO3RR is a"two birds,one stone"approach,simultaneously removing NO3-pollutants and producing valuable ammonia(NH3).However,the strong coordination between the NO3-intermediate and the catalytic active sites seriously hinders the conversion efficiency.Here,we determined that,through encapsulation strategies,the carbon layer could weaken the NO3-intermediate binding to active sites,resulting in higher NH3 yields.We experimentally fabricated electrocatalysts,i.e.,Cu nanoparticles encapsulating(or loaded on)N-doped carbon nanofibers(NCNFs)called Cu@NCNFs(Cu-NCNFs),using electrostatic spinning.As a result,Cu@NCNFs can achieve NH3 yields of 17.08 mg/(h·mgcat)at a voltage of-0.84 V and a Faraday efficiency of 98.15％.Meanwhile,the electrochemical properties of the Cu nanoparticles on the surface of carbon fibers(Cu-NCNFs)are lower than those of the Cu@NCNFs.The in situ Raman spectra of Cu@NCNFs and Cu-NCNFs under various reduction potentials during the NO3RR process show that catalyst encapsulation within carbon layers can effectively reduce the adsorption of N species by the catalyst,thus improving the catalytic performance in the nitrate-to-ammonia catalytic conversion process.
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