Low-Coordinated Conductive ZnCu Metal-Organic Frameworks for Highly Selective H2O2 Electrosynthesis.

Direct electrosynthesis of hydrogen peroxide (H2O2) with high production rate and high selectivity through the two-electron oxygen reduction reaction (2e-ORR) offers a sustainable alternative to the energy-intensive anthraquinone technology but remains a challenge. Herein, a low-coordinated, 2D conductive Zn/Cu metal-organic framework supported on hollow nanocube structures (ZnCu-MOF (H)) is rationally designed and synthesized. The as-prepared ZnCu-MOF (H) catalyst exhibits substantially boosted electrocatalytic kinetics, enhanced H2O2 selectivity, and ultra-high Faradaic efficiency for 2e-ORR process in both alkaline and neutral conditions. Electrochemical measurements, operando/quasi in situ spectroscopy, and theoretical calculation demonstrate that the introduction of Cu atoms with low-coordinated structures induces the transformation of active sites, resulting in the beneficial electron transfer and the optimized energy barrier, thereby improving the electrocatalytic activity and selectivity.

Advanced Nanocarbons Toward two-Electron Oxygen Electrode Reactions for H2O2 Production and Integrated Energy Conversion.

Hydrogen peroxide (H2O2) plays a pivotal role in advancing sustainable technologies due to its eco-friendly oxidizing capability. The electrochemical two-electron (2e-) oxygen reduction reaction and water oxidation reaction present an environmentally green method for H2O2 production. Over the past three years, significant progress is made in the field of carbon-based metal-free electrochemical catalysts (C-MFECs) for low-cost and efficient production of H2O2 (H2O2EP). This article offers a focused and comprehensive review of designing C-MFECs for H2O2EP, exploring the construction of dual-doping configurations, heteroatom-defect coupling sites, and strategic dopant positioning to enhance H2O2EP efficiency; innovative structural tuning that improves interfacial reactant concentration and promote the timely release of H2O2; modulation of electrolyte and electrode interfaces to support the 2e- pathways; and the application of C-MFECs in reactors and integrated energy systems. Finally, the current challenges and future directions in this burgeoning field are discussed.

Sn Bulk Phase Doping and Surface Modification on Ti4 O7 for Oxygen Reduction to Hydrogen Peroxide.

Developing stable and highly selective two-electron oxygen reduction reaction (2e- ORR) electrocatalysts for producing hydrogen peroxide (H2 O2 ) is considered a major challenge to replace the anthraquinone process and achieve a sustainable green economy. Here, we doped Sn into Ti4 O7 (D-Sn-Ti4 O7 ) by simple polymerization post-calcination method as a high-efficiency 2e- ORR electrocatalyst. In addition, we also applied plain calcination after the grinding method to load Sn on Ti4 O7 (L-Sn-Ti4 O7 ) as a comparison. However, the performance of L-Sn-Ti4 O7 is far inferior to that of the D-Sn-Ti4 O7 . D-Sn-Ti4 O7 exhibits a starting potential of 0.769 V (versus the reversible hydrogen electrode, RHE) and a high H2 O2 selectivity of 95.7 %. Excitingly, the catalyst can maintain a stable current density of 2.43 mA ⋅ cm-2 for 3600 s in our self-made H-type cell, and the cumulative H2 O2 production reaches 359.2 mg ⋅ L-1 within 50,000 s at 0.3 V. The performance of D-Sn-Ti4 O7 is better than that of the non-noble metal 2e- ORR catalysts reported so far. The doping of Sn not only improves the conductivity but also leads to the lattice distortion of Ti4 O7 , further forming more oxygen vacancies and Ti3+ , which greatly improves its 2e- ORR performance compared with the original Ti4 O7 . In contrast, since the Sn on the surface of L-Sn-Ti4 O7 displays a synergistic effect with Tin+ (3≤n≤4) of Ti4 O7 , the active center Tin+ dissociates the O=O bond, making it more inclined to 4e- ORR.

A Computation-guided Design of Highly Defined and Dense Bimetallic Active Sites on a Two-dimensional Conductive Metal-organic Framework for Efficient H2O2 Electrosynthesis.

Electrochemical synthesis of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e--ORR) provides an alternative method to the energy-intensive anthraquinone method. Metal macrocycles with precise coordination are widely used for 2e--ORR electrocatalysis, but they have to be commonly loaded on conductive substrates, thus exposing a large number of 2e--ORR-inactive sites that result in poor H2O2 production rate and efficiency. Herein, guided by first-principle predictions, a substrate-free and two-dimensional conductive metal-organic framework (Ni-TCPP(Co)), composed of Co-N4 sites in porphine(Co) centers and Ni2O8 nodes, is designed as a multi-site catalyst for H2O2 electrosynthesis. The approperiate distance between the CoN4 and Ni2O8 sites in Ni-TCPP(Co) weakens the electron transfer between them, thus ensuring their inherent activities and creating high-density active sites. Meanwhile, the intrinsic electronic conductivity and porosity of Ni-TCPP(Co) further facilitate rapid reaction kinetics. Therefore, outstanding 2e--ORR electrocatalytic performance has been achieved in both alkaline and neutral electrolytes (>90%/85% H2O2 selectivity within 0-0.8 V vs. RHE and >18.2/18.0 mol g-1 h-1 H2O2 yield under alkaline/neutral conditions), with confirmed feasibility for water purification and disinfection applications. This strategy thus provides a new avenue for designing catalysts with precise coordination and high-density active sites, promoting high-efficiency electrosynthesis of H2O2 and beyond.

Electronic Metal-Support Interactions Boost *OOH Intermediate Generation in Cu/In2Se3 for Electrochemical H2O2 Production.

Two-electron oxygen reduction reaction (2e- ORR) is a promising method for the synthesis of hydrogen peroxide (H2O2). However, high energy barriers for the generation of key *OOH intermediates hinder the process of 2e- ORR. Herein, we prepared a copper-supported indium selenide catalyst (Cu/In2Se3) to enhance the selectivity and yield of 2e- ORR by employing an electronic metal-support interactions (EMSIs) strategy. EMSIs-induced charge rearrangement between metallic Cu and In2Se3 is conducive to *OOH intermediate generation, promoting H2O2 production. Theoretical investigations reveal that the inclusion of Cu significantly lowers the energy barrier of the 2e- ORR intermediate and impedes the 4e- ORR pathway, thus favoring the formation of H2O2. The concentration of H2O2 produced by Cu/In2Se3 is ~2 times than In2Se3, and Cu/In2Se3 shows promising applications in antibiotic degradation. This research presents a valuable approach for the future utilization of EMSIs in 2e- ORR.

Steering sp-Carbon Content in Graphdiynes for Enhanced Two-Electron Oxygen Reduction to Hydrogen Peroxide.

Compared to sp2-hybridized graphene, graphdiynes (GDYs) composed of sp and sp2 carbon are highly promising as efficient catalysts for electrocatalytic oxygen reduction into oxygen peroxide because of the high catalytic reactivity of the electron-rich sp-carbon atoms. The desired catalytic capacity of GDY, such as catalytic selectivity and efficiency, can theoretically be achieved by strategically steering the sp-carbon contents or the topological arrangement of the acetylenic linkages and aromatic bonds. Herein, we successfully tuned the electrocatalytic activity of GDYs by regulating the sp-to-sp2 carbon ratios with different organic monomer precursors. As the active sp-carbon atoms possess electron-sufficient π orbitals, they can donate electrons to the lowest unoccupied molecular orbital (LUMO) orbitals of O2 molecules and initiate subsequent O2 reduction, GDY with the high sp-carbon content of 50 at % exhibits excellent capability of catalyzing O2 reduction into H2O2. It demonstrates exceptional H2O2 selectivity of over 95.0 % and impressive performance in practical H2O2 production, Faraday efficiency (FE) exceeding 99.0 %, and a yield of 83.3 nmol s-1 cm-2. Our work holds significant importance in effectively steering the inherent properties of GDYs by purposefully adjusting the sp-to-sp2 carbon ratio and highlights their immense potential for research and applications in catalysis and other fields.

Validating ΔΔG Selectivity Descriptor for Electrosynthesis of H2O2 from Oxygen Reduction Reaction.

Understanding selectivity trends is a crucial hurdle in the developing innovative catalysts for generating hydrogen peroxide through the two-electron oxygen reduction reaction (2e-ORR). The identification of selectivity patterns has been made more accessible through the introduction of a newly developed selectivity descriptor derived from thermodynamics, denoted as ΔΔG introduced in Chem Catal. 2023, 3(3), 100568. To validate the suitability of this parameter as a descriptor for 2e-ORR selectivity, we utilize an extensive library of 155 binary alloys. We validate that ΔΔG reliably depicts the selectivity trends in binary alloys reported for their high activity in the 2e-ORR. This analysis also enables the identification of nine selective 2e-ORR catalysts underscoring the efficacy of ΔΔG as 2e-ORR selectivity descriptor. This work highlights the significance of concurrently considering both selectivity and activity trends. This holistic approach is crucial for obtaining a comprehensive understanding in the identification of high-performance catalyst materials for optimal efficiency in various applications.

High-efficiency Electroreduction of O2 into H2 O2 over ZnCo Bimetallic Triazole Frameworks Promoted by Ligand Activation.

Co-based metal-organic frameworks (MOFs) as electrocatalysts for two-electron oxygen reduction reaction (2e- ORR) are highly promising for H2 O2 production, but suffer from the intrinsic activity-selectivity trade-off. Herein, we report a ZnCo bimetal-triazole framework (ZnCo-MTF) as high-efficiency 2e- ORR electrocatalysts. The experimental and theoretical results demonstrate that the coordination between 1,2,3-triazole and Co increases the antibonding-orbital occupancy on the Co-N bond, promoting the activation of Co center. Besides, the adjacent Zn-Co sites on 1,2,3-triazole enable an asymmetric "side-on" adsorption mode of O2 , favoring the reduction of O2 molecules and desorption of OOH* intermediate. By virtue of the unique ligand effect, the ZnCo-MTF exhibits a 2e- ORR selectivity of ≈100 %, onset potential of 0.614 V and H2 O2 production rate of 5.55 mol gcat -1 h-1 , superior to the state-of-the-art zeolite imidazole frameworks. Our work paves the way for the design of 2e- ORR electrocatalysts with desirable coordination and electronic structure.

Metastable Hexagonal Phase SnO2 Nanoribbons with Active Edge Sites for Efficient Hydrogen Peroxide Electrosynthesis in Neutral Media.

Electrochemical two-electron oxygen reduction reaction (2 e- ORR) to produce hydrogen peroxide (H2 O2 ) is a promising alternative to the energetically intensive anthraquinone process. However, there remain challenges in designing 2 e- ORR catalysts that meet the application criteria. Here, we successfully adopt a microwave-assisted mechanochemical-thermal approach to synthesize hexagonal phase SnO2 (h-SnO2 ) nanoribbons with largely exposed edge structures. In 0.1 M Na2 SO4 electrolyte, the h-SnO2 catalysts achieve the excellent H2 O2 selectivity of 99.99 %. Moreover, when employed as the catalyst in flow cell devices, they exhibit a high yield of 3885.26 mmol g-1 h-1 . The enhanced catalytic performance is attributed to the special crystal structure and morphology, resulting in abundantly exposed edge active sites to convert O2 to H2 O2 , which is confirmed by density functional theory calculations.

Synergetic Dual-Ion Centers Boosting Metal Organic Framework Alloy Catalysts toward Efficient Two Electron Oxygen Reduction.

Herein, a strategy of synergetic dual-metal-ion centers to boost transition-metal-based metal organic framework (MOF) alloy nanomaterials as active oxygen reduction reaction (ORR) electrocatalysts for efficient hydrogen peroxide (H2 O2 ) generation is proposed. Through a facile one-pot wet chemical method, a series of MOF alloys with unique Ni-M (M-Co, Cu, Zn) synergetic centers are synthesized, where the strong metallic ions 3d-3d synergy can effectively inhibit O2 cleavage on Ni sites toward a favorable two-electron ORR pathway. Impressively, the well-designed NiZn MOF alloy catalysts show an excellent H2 O2 selectivity up to 90% during ORR, evidently outperforming that of NiCo MOF (45%), and NiCu MOF (55%). Moreover, it sustains efficient activity and robust stability under a continuous longterm ORR operation. The correlative in situ synchrotron radiation X-ray adsorption fine structure and Fourier transform infrared spectroscopy analyses reveal at the atomic level that, the higher Ni oxidation states species, regulated via adjacent Zn2+ ions, are favorable for optimizing the adsorption energetics of key *OOH intermediates toward fast two electron ORR kinetics.

Strongly Coupled Cobalt Diselenide Monolayers for Selective Electrocatalytic Oxygen Reduction to H2 O2 under Acidic Conditions.

Electrosynthesis of hydrogen peroxide (H2 O2 ) in the acidic environment could largely prevent its decomposition to water, but efficient catalysts that constitute entirely earth-abundant elements are lacking. Here we report the experimental demonstration of narrowing the interlayer gap of metallic cobalt diselenide (CoSe2 ), which creates high-performance catalyst to selectively drive two-electron oxygen reduction toward H2 O2 in an acidic electrolyte. The enhancement of the interlayer coupling between CoSe2 atomic layers offers a favorable surface electronic structure that weakens the critical *OOH adsorption, promoting the energetics for H2 O2 production. Consequently, on the strongly coupled CoSe2 catalyst, we achieved Faradaic efficiency of 96.7 %, current density of 50.04 milliamperes per square centimeter, and product rate of 30.60 mg cm-2 h-1 . Moreover, this catalyst shows no sign of degradation when operating at -63 milliamperes per square centimeter over 100 hours.

Synergy of oxygen reduction for H2O2 production and electro-fenton induced by atomic hydrogen over a bifunctional cathode towards water purification.

In the Electro-Fenton (EF) process, hydrogen peroxide (H2O2) is produced in situ by a two-electron oxygen reduction reaction (2e ORR), which is further activated by electrocatalysts to generate reactive oxygen specieces (ROS). However, the selectivity of 2e transfer from catalysts to O2 is still unsatisfactory, resulting in the insufficient H2O2 availability. Carbon based materials with abundant oxygen-containing functional groups have been used as excellent 2e ORR electrocatalysts, and atomic hydrogen (H*) can quickly transfer one electron to H2O2 in a wide pH range and avoiding the restrict of traditional Fenton reaction. Herein, nickel nanoparticles growth on oxidized carbon deposited on modified carbon felt (Ni/Co@CFAO) was prepared as a bifunctional catalytic electrode coupling 2e ORR to form H2O2 with H* reducing H2O2 to produce ROS for highly efficient degradation of antibiotics. Electrochemical oxidation and thermal treatment were used to modulate the structure of carbon substrates for increasing the electro-generation of H2O2, while H* was produced over Ni sites through H2O/H+ reduction constructing an in-situ EF system. The experimental results indicated that 2e ORR and H* induced EF processes could promote each other mutually. The optimized Ni/Co@CFAO with a Ni:C mass ratio of 1:9 exhibited a high 2e selectivity and H2O2 yield of 49 mg L-1. As a result, the designed Ni/Co@CFAO exhibited excellent electrocatalytic ability to degrade tetracycline (TC) under different aqueous environmental conditions, and achieved 98.5% TC removal efficiency within 60 min H2O2 and H* were generated simultaneously at the bifunctional cathode and react to form strong oxidizing free radicals •OH. At the same time, O2 gained an electron to form •O2-, which could react with •OH and H2O to form 1O2, which had relatively long life (10-6∼10-3 s), further promoting the efficient removal of antibiotics in water.

First-principles study of electrochemical H2O2 production on Pd-B40 single-atom catalyst.

Hydrogen peroxide (H2O2), a versatile green compound, is increasingly in demand. The electrochemical two-electron oxygen reduction reaction (2e- ORR) is a simple and environmentally friendly substitute method to the traditional anthraquinone oxidation method for H2O2 production. This study systematically investigates the 2e- ORR process on single transition metal atom-loaded boron fullerene (M - B40) using density functional theory calculations. In evaluating the stability of the catalysts, we found that Au, Pd, Pt, Rh, and Ir atoms adsorbed on hexagonal or heptagonal sites of B40 exhibit good stability. Among these, Pd-modified B40 heptagonal cavity (Pd-B40-heptagonal) demonstrates an ideal Gibbs free energy change for OOH* (4.49 eV) and efficiently catalyzes H2O2 production at a low overpotential (0.27 V). Electronic structure analysis reveals that electron transfer between Pd-B40-heptagonal and adsorbed O2 facilitates O2 activation. Additionally, the high 2e- ORR activity of Pd-B40-heptagonal is attributed to electron transfer from the Pd-d orbitals to the π* anti-bonding of p orbitals of OOH*, moderately activating the O-O bond. This study offers valuable understanding designing high-performance electrocatalysts for 2e- ORR.

A quadruple-strategy of modification on carbon nitride boosts oxygen reduction for high performance photocatalytic hydrogen peroxide production.

This paper reports a quadruple-strategy for material design, simultaneously applying morphology control, group modification, defect engineering and alkali metal doping to the design of catalysts, and successfully constructing irregular clusters of carbon nitride (pMNK-CN) with excellent photogenerated carrier separation performance and structural stability. The pMNK-CN is an irregular flower cluster-like morphology with a nanosheet structure on the surface, and the repolymerization process of the prepolymer in the microvoid of the metal salt gives it an open pore structure. With the help of essential characterization, it was confirmed that the heptazine unit in the backbone underwent partial decomposition due to the etching of metal salts at high temperatures, reducing the overall polymerization and introducing cyano and nitrogen vacancies. Meanwhile, the potassium ion embedded in the lattice can induce the growth of ordered structures and thus improve the short-range order. The pMNK-CN possesses a hydrogen peroxide production efficiency of 240.0 µmol·g-1·h-1 in pure water, which is 31 times higher than that of bulk carbon nitride. And the apparent quantum efficiencies of pMNK-CN in the 380 and 420 nm bands are 17.5 % and 14.8 % in the presence of isopropanol. The effects of each modification strategies on the electronic structure of carbon nitride were investigated using First-Principles, and it was demonstrated that the multiple modification strategies synergistically enhanced the optical absorption, photogenerated charge separation efficiency, and lowered the reaction energy barrier, thus greatly contributing to the oxygen reduction to hydrogen peroxide performance.

Sustainable electro-Fenton simultaneous reduction of Cr (VI) and degradation of organic pollutants via dual-site porous carbon cathode driving uncoordinated molybdenum sites conversion.

Simultaneous removal of heavy metals and organic contaminants remains a substantial challenge in the electro-Fenton (EF) system. Herein, we propose a facile and sustainable "iron-free" EF system capable of simultaneously removing hexavalent chromium (Cr (VI)) and para-chlorophenol (4-CP). The system comprises a nitrogen-doped and carbon-deficient porous carbon (dual-site NPC-D) cathode coupled with a MoS2 nanoarray promoter (MoS2 NA). The NPC-D/MoS2 NA system exhibits exceptional synergistic electrocatalytic activity, with removal rates for Cr (VI) and 4-CP that are 20.3 and 4.4 times faster, respectively, compared to the NPC-D system. Mechanistic studies show that the dual-site structure of NPC-D cathode favors the two-electron oxygen reduction pathway with a selectivity of 81 %. Furthermore, an electric field-driven uncoordinated Mo valence state conversion of MoS2 NA enchances the generation of dynamic singlet oxygen and hydroxyl radicals. Notably, this system shows outstanding recyclability, resilience in real wastewater, and sustainability during a 3 L scale-up operation, while effectively mitigating toxicity. Overall, this study presents an effective approach for treating multiple-component wastewater and highlights the importance of structure-activity correlation in synergistic electrocatalysis.

Efficient Electrosynthesis of Hydrogen Peroxide Using Oxygen-Doped Porous Carbon Catalysts at Industrial Current Densities.

Metal-free carbon catalysts (MFCCs) are one of the commonly used catalysts for electrocatalytic two-electron oxygen reduction (2e- ORR) synthesis of hydrogen peroxide (H2O2). Oxygen doping is an effective means to improve the performance of MFCCs, but the performance of oxygen-doped carbon catalysts is still not high enough, and the contribution of different oxygen functional groups (OFGs) to the catalytic performance is still inconclusive. In this paper, carbon-based catalysts with different oxygen contents and ratios of OFGs were prepared, and the high 2e- ORR activity of COOH + C-OH was demonstrated by combining the results of experiments and theoretical calculations. The prepared oxygen-doped carbon-based catalyst C-0.1M80 achieved an onset potential of 0.795 V (vs RHE), a selectivity of up to 98.2% (0.6 V vs RHE), and a H2O2 oxidation current of 1.33 mA cm-2 (0.5 V vs RHE) in a rotating ring-disk electrode test (0.1 M KOH solution), which was an outstanding performance in MFCCs. In a solid electrolyte flow cell, C-0.1M80 achieved a Faraday efficiency of 97.5% at 200 mA cm-2 with a corresponding H2O2 production rate of 123.7 mg cm-2 h-1. In addition, a flow cell stability test was performed at an industrial current density (100 mA cm-2) with an astounding 200 h of uninterrupted operation, also achieving an outstanding average Faradaic efficiency (95.8%).

The Still Elusive Role of Lightweight Doping in Carbon-Based Electrocatalysts for the Selective Oxygen Reduction Reaction to Hydrogen Peroxide.

The two-electron electrocatalytic oxygen reduction reaction (ORR) to hydrogen peroxide (H2O2) is a valuable alternative to the more conventional and energy-intensive anthraquinone process. From a circularity viewpoint, metal-free catalysts constitute a sustainable alternative for the process. In particular, lightweight hetero-doped C-materials are cost-effective and easily scalable samples that replace - more and more frequently - the use of critical raw elements in the preparation of highly performing (electro)catalysts. Anyhow, their large-scale exploitation in industrial processes still suffers from technical limits of samples upscale and reproducibility other than a still moderate comprehension of their action mechanism in the process. This concept article offers a comprehensive and exhaustive "journey" through the most representative lightweight hetero-doped C-based electrocatalysts and their performance in the 2e- ORR process. It provides an interpretation of phenomena at the triple-phase interface of solid catalyst, liquid electrolyte and gaseous oxygen based on the doping-driven generation of ideal electronic microenvironments at the catalyst surface.

Weakly Hydrophilic Imine-Linked Covalent Benzene-Acetylene Frameworks for Photocatalytic H2O2 Production in the Two-Phase System.

Conversing oxygen (O2) to hydrogen peroxide (H2O2) driven by solar energy is a promising H2O2 onsite production route but often short of efficient and durable photocatalysts. Herein, strong π-π conjugate polycyclic aromatic benzene and acetylene units have been constructed into new covalent organic frameworks (COFs) linked by imine C═N bonding. These COFs demonstrated two-dimensional hexagonal crystalline frameworks with higher crystallinity and larger surface area (>600 m2 g-1). Covalent benzene-acetylene frameworks possessed appropriate visible light-responsive band structure and the suppressed charge recombination rate. The -OH groups on their frameworks enable them to be weakly hydrophilic. As a result, it served as high-performance but durable photocatalysts for H2O2 production in the water-benzyl alcohol (BA) two-phase system. It delivered a H2O2 production rate of 1240 µmol h-1 gcat-1 and durable catalytic efficiency within 60 h, comparable to the best COF-based catalysts. This study provides an efficient two-phase photocatalytic system for H2O2 production based on weakly hydrophilic imine-linked benzene-acetylene organic photocatalysts.

Fabricating carbon quantum dots of graphitic carbon nitride vis ultrasonic exfoliation for highly efficient H2O2 production.

A promising and sustainable approach for producing hydrogen peroxide is the two-electron oxygen reduction reaction (2e- ORR), which uses very stable graphitic carbon nitride (g-C3N4). However, the catalytic performance of pristine g-C3N4 is still far from satisfactory. Here, we demonstrate for the first time the controlled fabrication of carbon quantum dots (CQDs)-modified graphitic carbon nitride carbon (g-C3N4/CQDs-X) by ultrasonic stripping for efficient 2e- ORR electrocatalysis. HRTEM, UV-vis, EPR and EIS analyses are in good consistent which prove the in-situ generation of CQDs. The effect of sonication time on the physical properties and ORR activity of g-C3N4 is discussed for the first time. The g-C3N4/CQDs-12 catalyst shows a selectivity of up to 95% at a potential of 0.35 V vs. RHE, which is much higher than that of the original g-C3N4 catalyst (88%). Additionally, the H2O2 yield is up to 1466.6 mmol g-1 in 12 h, which is twice as high as the original g-C3N4 catalyst. It is discovered that the addition of CQDs through ultrasonic improves the g-C3N4 catalyst's electrical conductivity and electron transfer capability in addition to its high specific surface area and distinctive porous structure, speeding up the reaction rate. This research offers a green method for enhancing g-C3N4 activity.

Preparation of oxidized acetylene black by high-temperature calcination for luminol efficient cathodic electrochemiluminescence.

The improvement of electrochemiluminescence (ECL) intensity in luminol, a classic electrochemiluminescent material, remains a controversial topic. In this study, synthesis of acetylene black oxide (ACETO) through simple air annealing was successful in introducing oxygen-containing groups and defects, which can act as active sites for the oxygen reduction reaction (ORR) and exhibit excellent catalytic activity. By introducing the two-electron (2e-) ORR into the cathode ECL system of luminol, integration of ACETO and luminol allows for in situ generation of dissolved oxygen into reactive oxygen species (ROS), thereby enhancing the ECL intensity of luminol. It is worth noting that iron-nitrogen-carbon (FeNC), as a secondary antibody (Ab2) label, can catalyze the decomposition of H2O2, the product of 2e- ORR, into ROS to achieve ECL amplification. Alpha-fetoprotein (AFP), an important tumor marker, was successfully detected with a detection limit of 0.01 pg/mL, indicating that this ECL signal amplification strategy has broad application prospects in biological analysis.