Competitive Reaction Research Articles

Cu3P/CoP Heterostructure for Efficient Electrosynthesis of Ammonia from Nitrate Reduction Reaction.

Electrocatalytic nitrate reduction (ENO3RR) for ammonia production is one of the potential alternatives to Haber-Bosch technology for the realization of artificial ammonia synthesis. However, efficient ammonia production remains challenging due to the complex electron transfer process in ENO3RR. In this study, we fabricated a Cu3P/CoP heterostructure on carbon cloth (CC) by electrodeposition and vapor deposition, which exhibits an exceptional ENO3RR performance in alkaline medium, and showcases a Faradaic efficiency of ammonia (FENH3) and an ammonia yield rate as high as 97.95% and 17,637.3 μg h-1 cm-2 at -0.9 V vs RHE. Moreover, Cu3P/CoP also has excellent catalytic activity for nitrite reduction to ammonia, with an FENH3 up to 98.31% at -0.7 V vs RHE. The experimental and theoretical calculations reveal and confirm that the formation of a heterogeneous interface between Cu3P and CoP effectively promotes the electron transfer, where Cu3P as an electron donor induces the decrease of electron density around Cu and results in an enhancement of NO2- adsorption, thereby accelerating the ENO3RR process while inhibiting the competitive hydrogen evolution reaction (HER). Moreover, the metal phosphide catalyst facilitates the water dissociation, which accelerates the abundant *H generation, thus enhancing the subsequent hydrogenation process toward ENO3RR.

Constructing Lewis Acid-Base Pairs to Boost Electrocatalytic Hydrogenation of p-Nitrobenzoic Acid to Valuable p-Aminobenzoic Acid Using Water as the Hydrogen Source.

Electrocatalytic hydrogenation of toxic nitrobenzene to value-added aniline is of great significance in addressing the issues of energy crisis and environmental pollution. However, it is a considerable challenging and crucial to develop highly efficient and earth-abundant transition metal-based electrocatalysts with superior durability for the electro-hydrogenation of nitrobenzene due to the competitive hydrogen evolution reaction (HER). In this work, a facile approach is designed and introduced to constructing an integrated self-supported heterostructured Co1- xNix(OH)(CO3)/Al(OH)3 nanoarrays (CoNiCH/Al(OH)3) for the electrocatalytic reduction of nitrobenzoic acid (PNBA) to p-aminobenzoic acid (PABA) and its electrocatalytic mechanism for PNBA reduction is investigated. This unique Lewis acid-base pairs with abundant oxygen vacancies (OVs) can effectively regulate the adsorption energy of PNBA and active hydrogen intermediates, facilitate the proton-coupled electrocatalytic reduction process, leading to the high activity and selectivity for PNBA to PABA. The optimal CoNiCH/Al(OH)3-0.5 exhibits outstanding performance for the electrocatalytic hydrogenation of PNBA to PABA with a yield of 92%, selectivity of 95% and Faraday efficiency (FE) of 92% at -0.545V (vs reversible hydrogen electrode, RHE) under 0.1m phosphate buffered solution (PBS) neutral electrolyte. Besides, it can maintain a high electrocatalytic activity for at least eight electrocatalytic cycle-test.

CO2 Electroreduction to Multicarbon Products Over Cu2O@Mesoporous SiO2 Confined Catalyst: Relevance of the Shell Thickness

AbstractDespite the advantage of high carbon utilization, CO2 electroreduction (CO2ER) in acid is challenged by the competitive hydrogen evolution reaction (HER). Designing confined catalysts is a promising strategy to suppress HER and boost CO2ER, yet the relationship between the confined structure and catalytic performance remains unclear, limiting rational design. Herein, using Cu2O@mesoporous SiO2 core‐shell catalysts as a well‐defined platform, a volcano‐shaped relationship is found between the thickness of mesoporous SiO2 layer and productivity of multicarbon (C2+) products in CO2 electroreduction. The optimal shell thickness of 15 nm is identified, with in situ spectroscopies and theoretical simulations attributing this to the trade‐off between the local alkalinity and CO2 concentration, arising from the nanoconfinement effect. At this optimal thickness, the Cu2O@ mesoporous SiO2 catalyst achieves a C2+ Faradaic efficiency of 83.1% ± 2.5% and partial current density of 687.8 mA cm−2 in acidic electrolytes, exceeding most reported catalysts. This work provides valuable insights for the rational design of confined catalysts for electrocatalysis.

Screening Oxidoreductase Activities of Nanozymes: Toward Activity‐Tailored Guidelines

Nanozymes (NZs) are nanomaterials able to mimic natural enzymes, offering the advantages of better durability, wider range of operational conditions, and easier functionalization. In addition, some NZs exhibit multiple enzyme‐like activities and effective tandem/self‐cascade reactions. In this context, metallic and metal–oxide nanoparticles are among the most promising candidates for biomedical/biotechnological applications, thanks to their efficient oxidoreductase activities. However, characterizing NZs is challenging because the experimental set‐up of different assays strongly influence their performances. Consequently, currently available literature provides limited understanding of the characteristics of the various NZs, especially in terms of activity‐related performance, hindering their optimal selection and applicative potential. Here, leveraging on accurate characterization methodology, we report a direct comparison of several NZs (gold‐Au, platinum‐Pt, palladium‐Pd, ceria, iron oxide) possessing multi‐enzymatic activities. Our main findings indicate that 1) PtNZs outperform the other tested NZs in catalase‐like activity; 2) Pt and PdNZs present superior superoxide dismutase‐like activity; 3) for peroxidase‐ and oxidase‐like activity, the best‐performing NZ is substrate‐dependent; 4) competitive reactions in multifunctional NZs play a key role in their specific performance, and AuNZs can be the optimal choice in some peroxidase/oxidase configurations; 5) metallic NZs are more efficient than metal‐oxide ones, but 6) ceria presents unique phosphatase‐like activity.

1D Magnetic Nickel‐Carbon Matrix Nanotube Composites Derived from Hydrogen‐Bonded Organic Frameworks and Metal–Organic Frameworks for Electromagnetic Wave Absorption

AbstractHydrogen‐bonded organic frameworks (HOFs) and metal–organic frameworks (MOFs) emerge as promising materials for electromagnetic wave (EMW) absorption, due to their high specific surface area and readily modifiable characteristics. In this study, 1D magnetic nickel‐carbon matrix nanotube composites (Ni‐HMCNTs) from a mixture of HOFs and MOFs (Ni‐HMNTs) for EMW absorption are synthesized. The Ni‐HMNTs are achieved via a one‐step method involving a single‐pot solvothermal reaction among melamine, trimeric acid, and nickel nitrate. This process involves a HOF‐to‐MOF transformation, characterized by the penetration of Ni ions into the HOF structure via a competitive coordination reaction, resulting in the hollow structure of Ni‐HMNTs. Subsequent calcination of Ni‐HMNTs yields Ni‐HMCNTs optimized for EMW absorption. Remarkably, with a filling degree of only 10 wt%, 1.2 Ni‐HMCNTs‐700 (heat‐treated at 700 °C) exhibits exceptional EMW absorption properties, with a minimum reflection loss (RLmin) value of −50.4 dB and a maximum effective absorption bandwidth (EAB) of 7.32 GHz (10.64–17.96 GHz). These findings pave the way for further exploration of magnetically modified HOFs/MOFs for EMW applications.

Boron modification of AuRh mesoporous nanotubes for electro-reduction of nitrogen to ammonia.

Electrocatalytic nitrogen reduction reaction (NRR) is a prospective tactics for ammonia synthesis. However, the development of highly active NRR electrocatalysts is still challenging owing to the difficult activation of nitrogen and competitive hydrogen evolution reaction (HER). Here, we synthesized boron-doped AuRh mesoporous nanotubes (B-AuRh MNTs) via dual-template method coupled with boron doping. The mesoporous nanotube structure has high specific surface area and excellent surface permeability. Thereby, the B-AuRh MNTs exhibit NH3 yield of 13.3 μg h-1 mg-1cat and Faraday efficiency of 22.5% under 0.1 M Na2SO4. The doping of boron with weak hydrogen adsorption can generate electronic effect, thus stimulating the activation of N2 molecules and effectively inhibiting HER. This study proposes a universal method for the preparation of boron-doped Pd-based catalysts, which is beneficial to improve the NRR performance.&#xD.

Electrocatalytic N2 Reduction Driven by Mo-Based Double-Atom Catalysts Anchored on Graphdiyne

An electrocatalytic nitrogen reduction reaction (eNRR) presents an appealing strategy for ammonia (NH3) production at ambient conditions. Through systematic density functional theory (DFT) calculations, the eNRR performance of 23 double-atom catalysts has been investigated. These catalysts are composed of a Mo atom and a transition metal atom anchored on the graphdiyne (GDY), and they are named MoM-GDYs. Among the 23 MoM-GDYs studied, 14 MoM-GDYs highlighted catalytic selectivity by inhibiting a competitive hydrogen evolution reaction (HER) and demonstrated commendable eNRR catalytic performance. MoRu-GDY, MoMo-GDY, MoFe-GDY and MoY-GDY exhibited excellent eNRR catalytic activity with limiting potentials of −0.05 V, −0.13 V, −0.21 V and −0.24 V, respectively. These 14 catalysts favor N2 adsorption compared to H and exhibit less negative UL than the −0.98 V benchmark of the stepped Ru(0001) surface. Among them, MoRu-GDY has the best catalytic activity with an UL of −0.05 V. The excellent catalytic performance originates from the synergistic effect of the dual catalytic sites, where the alternation of the consecutive and enzymatic paths effectively reduces the limiting potentials. In addition, the catalytic activity can be evaluated using ΔG*NH3 − ΔG*NH2 as a theoretical descriptor, while UL and the ΔG*NH3 − ΔG*NH2 fit coefficient R2 reached 0.99. These findings not only contribute to the development of dual-atom electrocatalysts for eNRR but also offer a valuable pathway for identifying new eNRR catalysts with high activity and selectivity.

Leveraging Interfacial Electric Field for Smart Modulation of Electrode Surface in Nitrate to Ammonia Conversion

AbstractThe efficiency of nitrate reduction reaction (NO3RR) at low nitrate concentration is predominantly hindered by the poor affinity of nitrate ions and competitive hydrogen evolution reaction (HER), particularly in neutral and acidic media. Here, an innovative strategy to leverage the interfacial electric field (IEF) is introduced to boost the NO3RR performance. By in situ constructing tannic acid‐metal ion (TA‐M2+) crosslinked structure on the electrode surface, the TA‐M2+‐CuO NW/Cu foam sample exhibits an exceptional Faraday efficiency of 99.4% at −0.2 V versus reversible hydrogen electrode (RHE) and 83.9% at 0.0 V versus RHE under neutral and acidic conditions, respectively. The computational studies unveil that the TA‐Cu2+ complex on the CuO (111) plane induces the increasing concentration of nitrate at the interface, accelerating NO3RR kinetics over HER via the IEF effect. This interfacial modulation strategy also contributes the enhanced ammonia production performance when it is employed on commercial electrode materials and flow reactors, exhibiting great potential in practical application. Overall, combined results illustrated multiple merits of the IEF effect, paving the way for future commercialization of NO3RR in the ammonia production industry.

Parallel (competitive) reactions of micelle formation and cyclodextrin–surfactant inclusion complex formation in aqueous solution: A consequence of the Gibbs–Duhem equation—invariance of the mass action law and the possibility of determining the equilibrium constant of the inclusion complex

The Gibbs–Duhem equation results in the independence between the standard Gibbs free energy of micelle formation and the standard Gibbs free energy of monocomponent surfactant’s and cyclodextrin’s (CD’s) inclusion complex formation in aqueous solution. The experimental data show that the surfactant’s critical micellar concentration increases in the presence of CD. At a constant temperature, the standard Gibbs free energy of micelle formation remains constant, irrespective of the presence of parallel competitive processes such as inclusion complex formation. This indicates that the critical micellar concentration remains unchanged at the corresponding concentration scale. As a result, the equilibrium constant for surfactant–CD inclusion complex formation can be determined by changing the critical micellar concentration in the presence and absence of CD. A graphical method for determining the equilibrium constant of the inclusion complex is also presented. An analytical approach for analyzing the influence of the formation of the inclusion complex with CD on the formation of the binary mixed micellar pseudophase is presented. Suppose that different values exist for the equilibrium constants of the formation of the inclusion complex for two surfactants from their binary mixture. In this case, there is a change in the initial mole fraction from the initial mixture of surfactants, which should be considered when applying the regular solution theory protocol when determining the parameters of a binary mixed micelle in the presence of CD.

From retaliation to resilience: tracing the path of earnings stability in competitive markets

Purpose The purpose of this paper is to develop a more comprehensive understanding of the consequences of retaliations and our evidence indicates that retaliations are beneficial for firms with supranormal earnings by making their higher earnings more persistent, but harmful for firms with subnormal earnings by slowing the recovery of their earnings. Design/methodology/approach This paper use annual Compustat files based on Fama-French 48 industry. The time-varying competitive reactions (CRs) for each firm are captured using quarterly rolling-window estimation across 41 windows with five years (i.e. 20 observations) in each window. This paper measure earnings persistence as the slope coefficient (ß1) from regressing future earnings on current earnings. The result remains qualitatively similar to the main findings when alternative measures of earnings persistence. Findings Abnormal earnings are expected to dissipate in the long run owing to competitive forces, but this paper show that more retaliatory CRs increase earnings persistence. This is good news for supranormal firms as they can sustain high profitability. However, it will be harder to revert subnormal earnings to the industry mean if such firms conduct more retaliatory CRs. This paper also show that these associations are stronger for less competitive industries. Research limitations/implications First, high earnings persistence per se would not be a major consideration in the firm’s strategic decisions but a natural by-product of such decisions spanning an extended period of operations. Second, though this paper focus on the period of 2004–2018 that includes the rebound after financial crisis in 2008, an extension of the observation period over a longer economic cycle would verify our results. Practical implications CRs are regarded as an evolving portfolio of dynamic marketing decisions and tools for strategic decisions in our study. It helps how firms manage competition over time to lengthen the superior performance. Also it helps the low-profitability firms attempting to improve profitability by showing nonretaliation may be a more appropriate strategy than retaliation. Social implications Firms in financial distress suffer from illiquidity, survival of firms is contingent on meeting their financial obligations, thus need for turnaround decisions. However, retaliations under financial distress can mitigate the effect of such turnaround decisions and thereby aggravate the situation. Originality/value Greater persistence extends the benefits of superior earnings, thus increasing the opportunities for value exploitation, but it may also restrict earnings recovery. This paper finds that the way that firms react within the competition explain the differences in earnings persistence. Although a large body of research has examined the static drivers (e.g. firm size and diversification) of the differential persistence of earnings, there has been little research on dynamic drivers that explicitly recognize the erosion process for earnings.

Three-dimensional DNA Walker-mediated polarity switching biosensor based on the heterostructure of COFs and CuO nanocube for the sensitive photoelectrochemical detection of silver

Herein, a novel photocurrent polarity switchable photoelectrochemical (PEC) biosensor was fabricated based on the formation of a heterojunction between CuO nanocubes and two-dimensional crystalline covalent organic frameworks (COFs) by cyano-substituted buta-1,3-diene linkage for the detection of silver ion (Ag+), exhibiting an excellent anti-interference capability toward redox substances. Different from most of the COFs that were crystallized by condensation of two components, the proposed PTP-COF was generated by two competitive reversible reactions between the three components 4,4′,4″,4′′′-(pyrene-1,3,6,8-tetrayl)tetrabenzaldehyde (PTBD), 2,2′-(1,4-phenylene)-diacetonitrile (PDT) and acetaldehyde, which not only increased the conjugated π system of framework to accelerate the charge transfer efficiency, but also had strong acid and alkali resistance and bioavailability. Impressively, by combining with Mg2+ DNAzyme triggered DNA walker amplification strategy, the designed PEC biosensor exhibited excellent detection performance for Ag+ range from 100 fM to 1 μM with a limit of detection as low as 35 fM. This work puts forward a new idea for eliminating negative background signals for sensing and expands the application of COFs in the PEC system.

Atomic Scale Cooperativity of Alloy Nanostructures for Efficient Nitrate Electroreduction to Ammonia in Neutral Media

AbstractElectrochemical nitrate reduction reaction (NO3RR) offers a route to balanced nitrogen cycle and sustainable ammonia production. However, unsatisfied performance in neutral media arising from competitive hydrogen evolution reaction and inefficient hydrogenation impede the further applications of NO3RR. Herein, the rational design of RuNi alloy nanostructures is reported. Benefited from the synergism effect between Ru and Ni, Ru20Ni80 alloy exhibits a high NH3 Faradaic efficiency of 98.02% at −0.35 V (vs reversible hydrogen electrode (RHE)) and a large NH3 yield rate of 27.88 mg mgcat−1 h−1 at −0.65 V (vs RHE). Importantly, the atomic scale cooperation between Ru and Ni active sites endows RuNi alloy a close‐to‐unity NH3 selectivity via HNO* pathway. Theoretical calculations have revealed that the interactions between Ru and Ni optimize the electronic structures of Ru20Ni80 alloy, where Ru sites with enhanced electroactivity improve the generation of active hydrogens and more electron‐rich Ni sites facilitate the reduction of nitrate. Accordingly, the adsorption strengths of key intermediates become stronger and the energy barriers of NO3RR are reduced to guarantee efficient NO3RR. Furthermore, a flow‐type reactor coupled with coprecipitation is established to achieve continuous NH3 generation and recovery as struvite.

Synergistic Fe/Fe3C@Fe‐NC@Carbon Nanotube Heterostructure for Enhanced CO2 Capture and Mineral Recovery from Desalination Brine

AbstractMetal recovery coupled with CO2 mineralization from sustainable sources, such as seawater, has garnered significant attention from environmental science and resource utilization perspectives. Herein, an earth‐abundant and efficient Fe/Fe3C@Fe‐N‐codoped carbon@carbon nanotube (Fe/Fe3C@Fe‐NC@CNT) hybrid cathodic catalyst is introduced for electrochemically extracting magnesium and calcium from desalination brine while capturing CO2 to produce valuable Mg(OH)2 and CaCO3. The Fe/Fe3C@Fe‐NC@CNT, featuring the combination of single‐atomic Fe sites and graphitic layer‐wrapped Fe/Fe3C nanoparticles encapsulated within N‐doped mesoporous carbon tubes, achieves over 90% of Ca2+ and Mg2+ metal cations recovery efficiency at 25 mA cm−2 for 6 h. More importantly, the Fe/Fe3C@Fe‐NC@CNT hybrid catalyst efficiently suppresses the competitive hydrogen evolution side reaction even at high currents and boasts a wider operating potential range compared to benchmark Pt/C, enhancing the metal recovery efficiency and CO2 capture capability. These findings underscore the potential of the Fe/Fe3C@Fe‐NC@CNT hybrid catalyst in revolutionizing brine management and waste stream handling, offering a promising and sustainable solution to these critical environmental challenges.

Pd-Based Metal-Support Heterostructure Catalyst for High Performance Electrocatalytic N2 Reduction Reaction

Electrocatalytic nitrogen (N2) reduction reaction (eNRR) is of great interest to produce the green ammonia (NH3). However, the competitive side reaction of hydrogen (H2) evolution reaction (HER) and slow proton-couple electron transfer (PCET) step still become a bottleneck where resulting in poor N2 selectivity and yield of NH3 production. The heterostructures of metal and boron nitride (BN) analogs have been computatively demonstrated and suggested as a potential eNRR catalyst to improve eNRR performance as both suppressing HER and accelerating PCET step. However, experimental demonstration is still challenging due to the complex synthetic method required to achieve a uniform and dense distribution of metal catalysts on the BN surface. Here, we present the facile and uniform formation of the Pd nanoparticles (NPs) on defective boron nitride (BN) using ultrafast radiative Joule-heating within short time (~0.5 s), which is the first-time demonstration on the BN family. Especially, thanks to the strong electronic metal-to-support interaction (EMSI) effect between the defect site of BN surface and Pd NPs, the electron-deficient state of Pd NPs facilitates the significant reduce of free energy during the PCET step which is beneficial to interact with N2 molecules. In particular, we observe that Pd NPs on defective BN support exhibit the high NH3 selectivity of 68% in the neutral aqueous electrolyte and 59% of NH3 selectivity and 53.3 µg/h/cm2 of NH3 yield rate in the acidic media, respectively, which are the highest values of the selectivity and NH3 yield rate among existing Pd-based eNRR catalysts.

Structural and Electronic Modulations of Se-Vacancy-Rich MoSe2 Triggered by Cr Doping toward Robust Nitrogen Reduction Reaction.

The electrocatalytic nitrogen reduction reaction (NRR) is proposed as an alternative to the Haber-Bosch process, but the development of efficient NRR electrocatalysts remains a challenging task. MoSe2 has superior conductivity compared to MoS2, making it promising in the NRR field. Unfortunately, the scarcity of active sites and competitive hydrogen evolution reaction (HER) hinder its broader applications. Here, Se-vacancy-rich MoSe2 is designed through Cr doping, allowing for targeted regulations of architectural and electronic structure by leveraging the dual effects of doping and VSe. Further mechanistic studies innovatively find that the Cr-induced multi-vacancy (18.75% concentration) exerts inverse contributions to NRR on 2H- and 1T-MoSe2, reflecting boosted and depressed effects, respectively. Consequently, suitable doping effectively facilitates NRR and eases the competition from HER, realizing excellent NH3 yield (51.53±2.45µgh-1mg-1 cat) and Faradaic efficiency (63.37%) in MSC-1. This work paves the opportunity for MoSe2-based electrocatalysts toward boosted NRR.

High-Entropy Metal Sulfide Promises High-Performance Carbon Dioxide Reduction.

The efficient conversion of carbon dioxide (CO2) requires the development of stable catalysts with high selectivity and reactivity within a wide potential range. Here, the high-entropy metal sulfide CuAgZnSnS4 is designed for CO2 reduction with excellent performance (FEcarbonproducts ≥ 90%) in whole test potential windows (600 mV) based on the synergistic effect of the high-entropy metal sulfide. In particular, CuAgZnSnS4 exhibits better single-product selectivity with the highest FEHCOOH/FECO value (29.03) at -1.28 versus reversible hydrogen electrode (RHE). In combination with in situ measurements and theoretical calculations, it is further revealed that the synergistic effect of CuAgZnSnS4 realizes the controllable regulation of the surface electronic structure at Sn active sites, strengthening orbital interactions between *OCHO and Sn active sites. As a result, the effective adsorption and activation of *OCHO instead of *H are obtained, improving the single-product selectivity of electrocatalytic CO2 reduction and inhibiting the competitive hydrogen evolution reaction significantly. Our findings may complete the understanding of the synergistic effect for high-entropy materials in catalysis and offer new insight into the design of efficient electrocatalysts with high catalytic activity.

High surface density of Mn-N sites in atomically dispersed Mn catalyst for effective CO2 electroreduction

Electrocatalytic CO2 reduction to chemical fuels driven by renewable energy provides a highly promising route to fabricate the circular economy. However, the high overpotential and competitive side reactions severely hinder the industrial application of this process. Here we prepare the atomically dispersed Mn catalyst with high surface density of Mn-N sites via carbon protection and pyrolysis strategies, which exhibits a maximum of 90 % CO faradaic efficiency and the low overpotential of 80 mV to produce CO. The enhanced catalytic performance is mainly attributed to the high surface density of Mn-N4 sites, abundant defects, and high electrochemical active surface area. This work provides the possibility to improve the CO2 electroreduction performance of inert catalysts through surface structure design.

Stellar Thermonuclear Reaction Rates of Proton Radiative Capture by Closed Light Shell Isotopes

Light isotopes, especially closed shell nuclei, have significance in thermonuclear reactions of the Carbon-Nitrogen-Oxygen (CNO) cycle in stars. In this research, 12C(p, γ) 13N and 14N(p, γ) 15O reactions have been calculated by means of Matlab codes to find the reaction rate across a temperature range of 0.006 to 10 GK using non-resonant parts, as well as the astrophysical S- factor S(E) at low energies. It was concluded that the high binding energy of 12C and 14N nuclei make the reaction less probable thus enabling other competitive processes to develop, which enhances the probability of other competitive proton reactions in the CNO cycle.

Pd-Catalyzed Aromatic Dual C-H Acylations and Intramolecular Cyclization: Access to Quinoline-Substituted Hydroxyl Isoindolones.

A palladium-catalyzed aromatic dual C-H acylations followed with intramolecular cyclizations have been developed by the assistance of bidentate N-(quinolin-8-yl)benzamide. This tandem process involves the formation of three new chemical bonds, providing access to novel quinoline-substituted hydroxyl isoindolones skeleton under simple reaction conditions. The deuterium-labeled competition reaction has revealed that C-H bond cleavage is the turnover limiting step.

Rapid Preparation of a Self-Luminous Cd-Based Metal-Organic Framework Using AIEgen Ligands for High-Performance Electrochemiluminescence.

The design and synthesis of high-efficiency electrochemiluminescence (ECL) emitters hold great promise for a wide range of analytical applications. In this study, we developed a rapid and straightforward strategy to fabricate a self-luminous Cd-based metal-organic framework (Cd-MOF) using individual aggregation-induced emission ligands, specifically 1,1,2,2-tetrakis(4-(pyridin-4-yl)phenyl)ethane (TPPE), within a few seconds. The rigid and directionally enriched metal node of Cd, along with the organic ligands, is formed within the Cd-MOF via coordination, effectively constraining the intramolecular free motions of TPPE and suppressing nonradiative relaxation. Additionally, the unique porous structure combined with the catalytic activity resulting from the incorporation of Cd2+, endow the Cd-MOF with 90-fold ECL enhancement compared to individual TPPE as more chromophores are electro-excited and more coreactants are catalyzed to produce luminescence. The as-made Cd-MOF amplifies the ECL performance by integrating ECL emitters and coreactant accelerators into a single entity, simplifying the sensing process. Leveraging the excellent ECL performance, we constructed a sensitive ECL sensor for hydroquinone based on competitive reactions, with a wide linear range from 200 nM to 1 mM and a satisfying detection limit as low as 80 nM.