Boosting nitrogen electrocatalytic fixation by three-dimensional TiO_(2-δ)N_δnanowire arrays

Owing to the environmental and inherent advantages,nitrogen reduction reaction(NRR)by electrocatalysts attracts global attention.The surface engineering is widely employed to enhance the electrocatalytic activity by atomic defects and heterostructure effects.A three-dimensional(3D)free-standing integrated electrode was fabricated by numerous nearly-single-crystal TiO_(2-δ)N_δnanowire arrays.Based on the high electronic conductivity network,it exposes numerous active sites as well to facilitate the selective nitrogen adsorption and*H adsorption suppression.The synergistic effects between Ti^(3+)and oxygen vacancy(O_v)boost the intrinsic catalytic activity,in which Ti^(3+)acquired electrons via Ovcan effectively activate the N≡N bond and make it easy to bind with protons.The energy barrier of primary protonation process(*N_(2)+H^(+)+e^(-)→*NNH)can be dramatically decreased.The highest ammonia yield rate(14.33μg h^(-1)mgcat^(-1))emerges at-0.2 V,while the optimal ammonia Faradaic efficiency(9.17%)is acquired at-0.1 V.Density functional theory(DFT)calculation reveals that the Ti^(3+)can be served as the active sites for nitrogen adsorption and activation,while ammonia synthesis is accomplished by the distal pathway.The high electronic conductivity integrated network and synergistic effects can significantly facilitate nitrogen absorption and accelerate electrocatalytic reaction kinetic,which are responsible for the excellent NRR performance at room temperature.