Exploring nitrogen reduction reaction mechanisms in electrocatalytic ammonia synthesis:A comprehensive review

The electrochemical nitrogen reduction reaction(eNRR)holds significant promise as a sustainable alternative to the conventional large-scale Haber Bosch process,offering a carbon footprint-free approach for ammonia synthesis.While the process is thermodynamically feasible at ambient temperature and pressure,challenges such as the competing hydrogen evolution reaction,low nitrogen solubility in electrolytes,and the activation of inert dinitrogen(N_(2))gas adversely affect the performance of ammonia production.These hurdles result in low Faradaic efficiency and low ammonia production rate,which pose obstacles to the commercialisation of the process.Researchers have been actively designing and proposing various electrocatalysts to address these issues,but challenges still need to be resolved.A key strategy in electrocatalyst design lies in understanding the underlying mechanisms that govern the success or failure of the electrocatalyst in driving the electrochemical reaction.Through mechanistic studies,we gain valuable insights into the factors affecting the reaction,enabling us to propose optimised designs to overcome the barriers.This review aims to provide a comprehensive understanding of the various mechanisms involved in eNRR on the electrocatalyst surface.It delves into the various mechanisms such as dissociative,associative,Mars-van Krevelen,lithium-mediated nitrogen reduction and surface hydrogenation mechanisms of nitrogen reduction.By unravelling the intricacies of eNRR mechanisms and exploring promising avenues,we can pave the way for more efficient and commercially viable ammonia synthesis through this sustainable electrochemical process by designing an efficient electrocatalyst.

Correlating the crystal structure and facet of indium oxides with their activities for CO_(2)electroreduction

Constructing structure-function relationships is critical for the rational design and development of efficient catalysts for CO_(2) electroreduction reaction(CO_(2)RR).In_(2)O_(3) is well-known for its specific ability to produce formic acid.However,how the crystal phase and surface affect the CO_(2)RR activity is still unclear,making it difficult to further improve the intrinsic activity and screen for the most active structure.In this work,cubic and hexagonal In_(2)O_(3) with different stable surfaces((111)and(110)for cubic,(120)and(104)for hexagonal)are investigated for CO_(2)RR.Theoretical results demonstrate that the adsorption of reactants on cubic In_(2)O_(3) is stronger than that on hexagonal In_(2)O_(3),with the cubic(111)surface being the most active for CO_(2)RR.In experiments,synthesized cubic In_(2)O_(3) nanosheets with predominantly exposed(111)surfaces exhibited a high HCOO^(-)Faradaic efficiency(87.5%)and HCOO^(–)current density(–16.7 mA cm^(-2))at–0.9 V vs RHE.In addition,an aqueous Zn-CO_(2) battery based on a cubic In2O3 cathode was assembled.Our work correlates the phases and surfaces with the CO_(2)RR activity,and provides a fundamental understanding of the structure-function relationship of In_(2)O_(3),thereby contributing to further improvements in its CO_(2)RR activity.Moreover,the results provide a principle for the directional preparation of materials with optimal phases and surfaces for efficient electrocatalysis.

The mechanism of unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to l,2,3,4-tetrahydrofuro[3,4-b]-pyridin-5(7H)-one with sodium borohydride

An unexpected reduction of dimethyl pyridine-2,3-dicarboxylate to 1,2,3,4-tetrahydrofuro[3,4-b]pyridin-5（7H）-one with sodium borohydride in ethanol and tetrahydrofuran, respectively, is described, a hypothetic mechanism for the unusual reductive product is proposed.