Investigation On The Confinement Synthesis Of 2D Array Electrodes Based On Ldhs And Their Electrocatalytic Reduction Performance

Developing efficient electrocatalysts is crucial in electrocatalysis research for achieving clean energy transformation.2D nanomaterials,known for their high specific surface area and unique physicochemical properties,emerge as significant electrocatalytic materials.The preparation methods for 2D nanomaterials mainly include"top-down"exfoliation and"bottom-up"synthesis,yet these approaches are often constrained by the inherent 2D structural properties of the materials.In recent years,confinement synthesis strategies have opened up new avenues for the customized synthesis of 2D nanomaterials.This approach employs 2D micro/nano reactors as confining agents,enabling the direct specification of material physical dimensions and the modulation of their chemical properties.However,this strategy still faces the following limitations and challenges:（1）The confinement synthesis of 2D nanomaterials requires the rational selection of both 2D host and guest materials to achieve precise construction and modulation of the size,thickness,and active sites of the 2D nanomaterials.However,a comprehensive understanding of the matching relationship between host-guest materials is still lacking.（2）Presently,the majority of 2D nanomaterials prepared via confinement synthesis exist in powder form,prone to aggregation during electrode preparation.This aggregation leads to the burial of active sites and a decrease in mass transfer capability.Direct preparation of 2D array electrodes through confinement synthesis presents an effective strategy to address these issues,yet systematic studies are still lacking.（3）The intrinsic catalytic performance of 2D nanomaterials obtained via confinement synthesis is limited.Enhancing the intrinsic activity of catalytic sites and further strengthening their electrocatalytic performance remains a challenging task in material design.Additionally,this limitation impedes the in-depth understanding of key active species and reaction mechanisms during electrocatalytic reactions.Addressing the issues,this study delves into the confinement synthesis of 2D array electrodes and the electrocatalytic reduction performance of small molecules.LDHs is chosen as the 2D confinement host.Leveraging LDHs’unique intercalation structure,ordered arrangement of layer metal elements,and its topological transformation characteristics,the controlled preparation of 2D carbon nanosheet array electrodes is achieved.Furthermore,customization and modulation of the active species（single atoms,phosphides,and sulfides）on the fabricated 2D array electrodes are realized.The research demonstrates that the prepared 2D array electrodes exhibit outstanding performance in electrocatalytic oxygen reduction and nitrate reduction reactions.Furthermore,it comprehensively reveals a novel key mechanism governing the dynamic balance of active hydrogen,influencing the efficiency and selectivity of electrocatalytic reduction reactions.This study offers guidance for further optimization and design of electrode materials.The specific research contents are as follows:1.Confinement synthesis of IE-SACs based on LDHs for electrocatalytic ORRRegarding the controlled preparation of 2D array electrodes,this paper first synthesized a Co Al-LDH array with co-intercalated p-toluenesulfonate（PA）and m-aminobenzenesulfonate（MA）.Leveraging the topological transformation characteristics of LDHs,orderly interlayer guest molecules achieved in situ carbonization conversion within the confined space（interlayer distance of 1.56 nm）.Simultaneously,layer metal elements were uniformly dispersed into the carbon nanosheet framework,thereby obtaining ultra-thin carbon nanosheet arrays loaded with Co single atoms（IE-SACs）.The study found that organic guest molecules intercalated in LDHs precursors could effectively regulate the coordination structure of Co sites in IE-SACs:amino groups in MA molecules facilitated the formation of Co-N structures,thereby enhancing intrinsic activity;while PA molecules increased the number of active sites through pore formation.Thus,the prepared IE-SAC electrode combines intrinsic activity of Co sites,high specific surface area,and abundant pore structure,exhibiting excellent electrocatalytic activity in the oxygen reduction reaction.The obtained 2D array self-supporting electrode can also directly serve as the positive electrode of a zinc-air battery,demonstrating a high specific capacity of690.3 m Ah g^-1 and a high energy density of 963.3 Wh kg^-1with stability.Correspondingly,the flexibility of quasi-solid-state battery devices is outstanding,showing promising applications in wearable electronics.The strategy of hydrotalcite confinement synthesis of 2D array electrodes proposed in this chapter is also expected to be applied to the controlled synthesis of other structured electrodes.2.Confinement synthesis of CoP-CNS based on LDHs for electrocatalytic NITRRTo further expand the universality of LDHs confined synthesis array electrodes,a carbon nanosheet array electrode loaded with metal cobalt nanoparticles was prepared through the LDHs confined synthesis strategy.The metal Co particles were transformed in situ into highly dispersed CoP nanoparticles through phosphorization treatment,resulting in a carbon nanosheet array electrode loaded with phosphorized cobalt nanoparticles（CoP-CNS）.The obtained CoP-CNS array electrode exhibits excellent electrocatalytic performance for NITRR,with a maximum NH₃ production rate of 8.47 mmol h^-1 cm^-2 and a high FE of 88.6%,and a stable operation time exceeding 123 h,which is the optimal value reported in the same period.Through orthogonal experiments,electron spin resonance,isotope kinetics,in situ infrared spectroscopy,and theoretical calculations,it was demonstrated that the high-level dynamic equilibration between the generation and consumption of H_ads at the CoP site is the key to enhancing the NITRR performance for NH₃ production.Based on the high NITRR performance of CoP-CNS,an improved scheme for capturing carbon dioxide in flue gas using electrocatalytic NH₃ production was proposed,demonstrating the practical application potential of the obtained array electrode.This chapter expands the universality of LDHs confinement synthesis strategy and proposes a new mechanism of H_ads dynamic balance,providing guidance for the design and mechanism elucidation of high-performance catalysts for NITRR.3.Confinement synthesis of Co-MoS₂-CNS based on LDHs for electrocatalytic NITRRThe preceding research showcases the significant potential of employing 2D array electrodes synthesized via LDHs confinement for NH₃production in NITRR.Nonetheless,these materials are prone to corrosion deactivation in acidic conditions,constraining their practical utility.This chapter further constructs Co-doped MoS₂ loaded carbon nanosheet array electrode with multi-level array structures by hydrothermal growth of MoS₂secondary structures on electrode that prepared by confinement synthesis based on LDHs,termed as Co-MoS₂-CNS.During MoS₂ growth,Co species doping into the MoS₂ lattice achieves self-stabilization,resulting in excellent NITRR activity and stability across the entire p H spectrum for Co-MoS₂-CNS.Under acidic conditions,Co-MoS₂-CNS efficiently produces NH₃ with a 90%FE and a yield rate of 0.55 mmol h^-1 cm^-2.In neutral and alkaline environments,it achieves NH₃ production rates of 0.84 mmol h^-1 cm^-2 and2.08 mmol h^-1 cm^-2,respectively,rendering Co-MoS₂-CNS a versatile NITRR catalyst applicable across various p H levels.Further elucidation through in situ impedance,quartz crystal microbalance,and other methods reveals the universality of the H_ads dynamic balance mechanism across the entire p H spectrum,paving the way for new avenues in NITRR and other small molecule reduction reaction system design.This section enriches the tunability of LDHs confined synthesis array electrode strategy and contributes valuable insights for the construction and modulation of novel composite array materials.