Superior Electrocatalytic Activity Research Articles

Engineering Water-Lotus-like Iridium-Cobalt Carbonate Hydroxides on Plasma-Treated Carbon Fibers for Enhanced Electrocatalytic Oxygen Evolution.

The sluggish kinetics of the oxygen evolution reaction (OER) in alkaline water electrolysis remains a significant challenge for developing high-efficiency electrocatalytic systems. In this study, we present a three-dimensional, micrometer-sized iridium oxide (IrO2)-decorated cobalt carbonate hydroxide (IrO2-P-CoCH) electrocatalyst, which is engineered in situ on a carbon cloth (CC) substrate pretreated with atmospheric-pressure dielectric barrier discharge (DBD) plasma (PCC). The electrocatalyst features petal-like structures composed of nanosized rods, providing abundant reactive areas and sites, including the oxygen vacancy caused by the air-DBD plasma. As a result, the IrO2-P-CoCH/PCC electrocatalyst demonstrates an outstanding OER performance, with overpotentials of only 190 and 300 mV required to achieve current densities of 10 mA cm-2 (j10) and 300 mA cm-2 (j300), respectively, along with a low Tafel slope of 48.1 mV dec-1 in 1.0 M KOH. Remarkably, benefiting from rich active sites exposed on the IrO2-P-CoCH (Ir) heterostructure, the synergistic effect between IrO2 and CoCH enhances the charge delivery rates, and the IrO2-P-CoCH/PCC exhibits a superior electrocatalytic activity at a high current density (300 mV/j300) compared to the commercial benchmarked RuO2/PCC (470 mV/j300). Furthermore, the IrO2-P-CoCH/PCC electrocatalyst shows exceptional OER stability, with a mere 1.3% decrease with a current density of j10 for 100 h testing, surpassing most OER catalysts based on CC substrates. This work introduces a novel approach for designing high-performance OER electrocatalysts on flexible electrode substrates.

Ultrasensitive carbon nanotube-bridged MXene conductive network arrays for one-step homogeneous electrochemical immunosensing of tumor markers

Developing non-passivating and fully integrated electrode arrays for point-of-care testing of carcinoembryonic antigen (CEA) is crucial, as the serum level of CEA is closely associated with colorectal cancer. Herein, we propose a simple, low-cost, and eco-friendly template-assisted filtration method for the scalable preparation of carbon nanotube-bridged Ti3C2Tx MXene (MX@CNT) electrode arrays with a conductive network. Furthermore, we fabricate a homogeneous electrochemical (HEC) sensor for CEA detection by integrating a magnetic-bead-based alkaline phosphatase-linked immunoassay (MB-aElisa), which enables the in-situ generation of the electroactive substance 1-naphthol (1-NP). Benefiting from the unique electrochemical characteristics of a MX@CNT electrode array, such as ultra-low background signal and superior electrocatalytic activity towards the hydrolyzed 1-NP, the MB-aElisa-based HEC sensor specifically measures CEA within a detection range spanning from 0.005 to 1.0 ng mL−1, achieving a detection limit of 1.6 pg mL−1. Subsequently, this biosensing prototype is successfully utilized for the detection of CEA in serum specimens obtained from colorectal cancer patients. More importantly, the integration of MB-aElisa with a MX@CNT electrode array not only marks a significant advancement but also enables the creation of a one-step homogeneous electrochemical immunosensing platform, serving as a paradigm for the highly sensitive and selective measurement of trace tumor markers in complex biological samples.

NiSX/carbon black hybrids for efficient electrochemical oxidation of 5-hydroxymethyfurfural to 2,5-furandicarboxylic acid

NiSX stands out in the electrochemical oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) due to the favorable conductivity and diverse chemical composition. However, NiSX usually exhibits few exposed active sites and poor charge transfer kinetics. Moreover, during the electrochemical oxidation of HMF, the conductivity of the catalyst would decrease rapidly with the formation of oxidized Ni species, leading to a rapid decline in catalytic performance. Therefore, a series of NiSX/carbon black (CB) hybrids (NiSX/CB-n) were synthesized via a one-step solvent hydrothermal method in which NiSX displayed a large cubic block structure assembled from small nanosheets. Among the prepared catalysts, NiSX/CB-2, with the optimal amount of introduced CB, exhibited superior electrocatalytic activity for the oxidation of HMF, achieving 100% HMF conversion, 98% FDCA yield, and 100% Faradaic efficiency at 1.45 V (vs. RHE). The outstanding electrocatalytic activity of NiSX/CB-2 was attributed to the suitable CB doping, which not only enhanced the conductivity of catalyst but also separated the small nanosheets, preventing the formation of densely packed NiSX structure and increasing the specific surface area of catalyst, thereby exposing more active sites and improving the availability of material. Furthermore, the formation of C-S bonds facilitated charge interactions between NiSX and CB, promoting the transfer of charges during the electrolysis process and enhancing electrocatalytic kinetics. Open circuit potential tests demonstrated that the introduction of CB also strengthened the adsorption capacity of catalyst for HMF, further benefiting its electrocatalytic activity.

Fabrication of a free-standing Ti3C2T x -PTh counter electrode via interfacial polymerization for dye-sensitized solar cells.

The current work involves the fabrication of a MXene-Polythiophene (Ti3C2T x -PTh) composite via interfacial polymerization, alongside its deployment as a counter electrode (CE) or photocathode in dye-sensitized solar cells (DSSCs). The structural properties of the synthesized materials were investigated through a comprehensive array of techniques, including X-ray diffraction (XRD), fourier-transform infrared (FT-IR) spectroscopy, high resolution scanning electron microscopy (HRSEM), energy-dispersive X-ray analysis (EDAX), and X-ray photoelectron spectroscopy (XPS). The electrochemical performance, assessed via cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealed that the Ti3C2T x -PTh CE exhibits superior electro-catalytic activity, and reduction in charge transfer resistance compared to other individual CEs. These observations are in concordance with the data obtained from Tafel analysis. The incorporation of Ti3C2T x sheets into the composite significantly augmented its catalytic efficacy for triiodide reduction, manifesting in elevated short-circuit photocurrent density and enhanced fill factor metrics. A DSSC utilizing the Ti3C2T x -PTh CE exhibited a power conversion efficiency (PCE) of 5.83%, which stands on par with that of traditional Pt CEs. Thus, the Ti3C2T x -PTh CE material is posited as a viable, cost-efficient alternative to Pt, heralding a new era in the engineering of counter electrodes for the next generation of DSSCs.

Enhanced efficiency and stability of dye-sensitized solar cells utilizing FeCo2S4 nanowires as Pt-free counter electrodes

Replacing traditional Pt-based counter electrodes with low-cost and highly stable materials is crucial for the development of commercially viable dye-sensitized solar cells (DSSCs). In this study, we synthesized a ternary Pt-free FeCo2S4 nanowire (NW)-based sulfide electrocatalyst by a three-step solvothermal method. This material was then used as a counter electrode in DSSCs to facilitate the reduction of triiodide species. The formation of FeCo2S4 NW was confirmed by various characterization techniques such as X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Scanning electron microscopy analysis revealed the structure of the nanowires. Electrochemical studies, which included cyclic voltammetry, electrochemical impedance spectroscopy and Tafel polarization methods, revealed the excellent stability, superior electrocatalytic activity and remarkable kinetics of FeCo2S4 NW in the reduction of triiodide to iodide. Photovoltaic measurements of the fabricated DSSCs yielded a power conversion efficiency (PCE) of 7.88 % for the FeCo2S4-based devices, outperforming the control device made of Pt (PCE=7.45 %). This improvement was primarily due to the increase in short-circuit current density (JSC), thanks to the lower charge transfer resistance (RCT) of FeCo2S4 NW (JSC=15.23 mA/cm2; RCT=5.54 Ω cm2) compared to Pt (JSC=14.12 mA/cm2; RCT=7.07 Ω cm2). In addition, the FeCo2S4 NW-based solar cells exhibited excellent stability and maintained their high PCE value even after 10 days of aging under ambient conditions, while Pt-based DSSCs showed a 3 % decrease from their initial PCE value. This FeCo2S4 NW counter electrode proves to be an excellent alternative to Pt, and the presented results provide valuable insights for the development of cost-effective and highly stable DSSCs.

Electrodeposition in one step: Synthesizing Ir–Co tetradecahedral nanoparticles with high-index (311) crystal planes for enhanced catalytic activity in alkaline hydrogen evolution reaction

Electrochemical water splitting represents a viable route for hydrogen production, but its efficiency critically depends on developing effective electrocatalysts that minimize energy loss and material costs. This study introduces iridium-cobalt (Ir–Co) nanoparticles were synthesized on copper foam (CF) substrates using a one-step electrodeposition method. A comprehensive analysis was conducted on the morphology, chemical composition, and crystal structure of the electrocatalysts, along with a particular study on their electrocatalytic performance in the hydrogen evolution reaction (HER). The results demonstrate that high-index IrCo (311) crystal planes have been detected in the Ir–Co/CF electrocatalysts, which possess a tetradecahedral polycrystalline structure. The size of tetradecahedral nanoparticles is in the range of 180–250 nm. Ir–Co nanoparticles exhibit a balanced composition of approximately 49.8 at% Ir and 50.2 at% Co. The Ir–Co/CF electrocatalyst exhibits superior electrocatalytic activity in 1.0 M KOH solution, requiring only 46.8 mV overpotential to obtain a current density of 10 mA cm−2, with a low Tafel slope of 32.65 mV·dec−1. Additionally, the prolonged stability tests confirm the robustness of the Ir–Co/CF electrocatalyst, highlighting its potential for sustainable energy applications.

MOF derived M/Sn/N (M= Mg, Mn) based carbon nanospheres as highly efficient multicomponent electrocatalysts towards hydrogen evolution and photovoltaics

Constructing multicomponent electrocatalysts towards efficient energy conversion is widely adopted strategy, in this regard, high performance metal/nonmetal codoped carbon electrode materials have attained great consideration. Still, the electroacatalytic susceptibility, abundant intrinsic active sites, and stable electrochemical performance in different electrolytes are considered as underline challenges, which can be addressed by rational structural modifications to build a hybrid electroactive material. In this work, unique Sn based multicomponent carbon nanospheres are firstly developed as highly efficient bi-functional electrocatalysts in solar cells and hydrogen evolution. The designed electrocatalysts feature the combined effect of dispersed bimetal active sites and sufficient nitrogen components within spherical carbon framework, which readily enhanced the charge transfer rate via multiple channels, boosting the triiodide reduction reaction (IRR) and hydrogen evolution reaction (HER). As a result, solar cell with Mn/Sn-NC based counter electrodes (CEs) exhibited an excellent power conversion efficiency (PCE) of 8.39 %, outperforming Pt (7.67 %). Moreover, superior HER kinetics are also demonstrated by Mn/Sn-NC with a small overpotential of 127.8 mV at 10 mA cm−2 and tafel slope of 77 mV dec−1. The rational design of the carbon nanospheres with MnSn2 bimetal nanoparticles and N doping promotes a high electrochemically active surface area, low charge-transfer resistance, excellent electrochemical stability, and superior electrocatalytic activity, providing a promising route to construct highly efficient materials towards multiple energy conversion applications.

Ultra-Sensitive Simultaneous Detection of Dopamine and Acetaminophen over Hollow Porous AuAg Alloy Nanospheres.

Hollow porous AuAg nanospheres (AuAg HPNSs) were obtained through a simple solvothermal synthesis, complemented by a dealloying strategy. The hollow interior, open pore voids, and integral interconnected skeleton shell in AuAg HPNSs are beneficial for providing sufficient electrolyte diffusion and contacts, abundant active sites, and efficient electron transport. This specific structure and the favorable alloy synergism contribute to the superior electrocatalytic activity toward dopamine (DA) and acetaminophen (AC). AuAg HPNSs show high sensitivity, good selectivity, excellent sensing durability, and outstanding repeatability for amperometric assays of AC and DA. In particular, the AuAg-based sensors achieve effective ultrasensitive simultaneous analyses of AC and DA, exhibiting the characteristics of the wide linear range and low detection limit. With their prominent electrocatalytic activity and simple preparation methods, AuAg HPNSs present broad application prospects for constructing a highly responsive electrochemical sensing system.

Open Active Sites in Ni-Based MOF with High Oxidation States for Electrooxidation of Benzyl Alcohol.

The kinetics of electrocatalytic reactions are closely related to the number and intrinsic activity of the active sites. Open active sites offer easy access to the substrate and allow for efficient desorption and diffusion of reaction products without significant hindrance. Metal-organic frameworks (MOFs) with open active sites show great potential in this context. To increase the density of active sites, trimesic acid was utilized as a ligand to anchor more Ni sites and in situ construct the nickel foam-loaded Ni-based trimesic MOF electrocatalyst (Ni-TMA-MOF/NF). When tested as an electrocatalyst for benzyl alcohol oxidation, Ni-TMA-MOF/NF exhibited lower overpotential and superior durability compared to Ni foam-loaded Ni-based terephthalic MOF electrocatalyst (Ni-PTA-MOF/NF) and Ni(OH)2 nanosheet array (Ni(OH)2/NF). Ni-TMA-MOF/NF required only a low potential of 1.65 V to achieve a high current density of 400 mA cm-2. Even after 40000 s of electrocatalytic oxidation at 1.5 V, Ni-TMA-MOF/NF maintained a current density of 175 mA cm-2 with ∼68% retention, showing its potential for benzyl alcohol oxidation. Through a combination of experimental and theoretical investigations, it was found that Ni-TMA-MOF/NF displayed superior electrocatalytic activity due to an optimized electron structure with high-valence Ni species and a high density of active sites, enabling long-term stable operation at high current densities. This study provides a new perspective on the design of electrocatalysts for benzyl alcohol oxidation.

Pd-intercalated black phosphorus: An efficient electrocatalyst for CO2 reduction.

Nanoconfined catalysts enhance stabilization of reaction intermediates, facilitate electron transfer, and safeguard active centers, leading to superior electrocatalytic activity, particularly in CO2 reduction reactions (CO2RR). Despite their effectiveness, crafting nanoconfined catalysts is challenging due to unclear formation mechanisms. In this study, we introduce an electrochemical method to grow Pd clusters within the interlayers of two-dimensional black phosphorus, creating Pd cluster-intercalated black phosphorus (Pd-i-BP) as an electrocatalyst. Using in situ electrochemical liquid phase transmission electron microscopy (EC-TEM), we revealed the synthesis mechanism of Pd-i-BP, involving electrochemically driven Pd ion intercalation followed by reduction within the BP layers. The Pd-i-BP electrocatalyst exhibits exemplary CO2-to-formate conversion, achieving 90% Faradaic efficiency for formate production, owing to its distinct nanoconfined structure that stabilizes intermediates and enhances electron transfer. Density functional theory (DFT) calculations underscore the structural benefits for enhancing intermediate adsorption and catalyzing the reaction. Our insights deepen understanding of nanoconfined material synthesis, promising advanced, high-efficiency catalysts.

Hydrothermal synthesis of high-performance cobalt phosphate nanorod architecture as bifunctional electrocatalysts for rechargeable Zn-air batteries and supercapatteries

Transition metal phosphate bifunctional electrocatalysts demonstrate superior oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and capacitive properties owing to their high electrocatalytic and conductive activities. In this report, cobalt phosphate (Co3P2O8) nanorod (NR) electrocatalytic materials were developed via a facile one-step hydrothermal synthesis, followed by an annealing process. The unique NR structures offer superior electrocatalytic activities, continuous and quick electron transport pathways, short ion diffusion lengths, and rich active sites toward rechargeable zinc-air batteries (ZABs) and supercapatteries (SCs). The self-assembled Co3P2O8 NR electrocatalyst revealed higher current density values during the OER and ORR measurements than the commercially available Pt/C and IrO2 materials. The Co3P2O8 NR electrocatalyst exhibited an excellent OER overpotential of 180 mV. The electocatalyst also showed superior onset and half-wave potentials of 0.92 V and 0.80 V, respectively. Moreover, the fabricated Co3P2O8 NRs-based ZAB exhibited better durability than the Pt/C-based ZAB. Significantly, the Co3P2O8 NR electrode demonstrated an excellent specific capacity of 373 mAh g−1 with outstanding cycling stability of 99% after 5000 cycles. Additionally, the fabricated Co3P2O8 NRs//activated carbon SC demonstrated high specific energy and power densities of 25.62 Wh kg−1 and 2953.12 W kg−1, respectively with remarkable cycling stability of 89% after 7000 cycles. Specifically, the practical applicability of the fabricated Co3P2O8 NRs-based ZAB and SC was tested using a blue light-emitting diode nameplate energized by two devices in series. Overall, the catalytic and energy-storage properties of the Co3P2O8 NR material can provide a new pathway for high-energy electrochemical applications.

Led-induced deposition of Pt and Au NPs on carbon fibers: Developing a novel strategy for facile fabrication of electrocatalysts for enhanced methanol electrooxidation

In addressing the imperative of aligning materials science with sustainable development, our study introduces an innovative method for the simultaneous deposition of Pt and Au nanoparticles onto a carbon support. This research represents the pioneering application of the photodeposition process for synthesizing bimetallic nanoparticles on a carbon matrix. The comprehensive characterization of the resulting nanostructures involves various techniques, including field X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), atomic force microscopy (AFM), energy-dispersive X-ray analysis (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-OES), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetric techniques. Our findings reveal that the photodeposition method produces a homogeneous AuPt nanostructure, demonstrating superior electrocatalytic activity in methanol oxidation compared to the monometallic carbon fiber_Pt (CF_Pt) catalyst. These results emphasize the effectiveness of our novel approach in fabricating electrocatalysts with exceptional performance in methanol oxidation reactions.

Explosive Leidenfrost-Droplet-Mediated Synthesis of Monodispersed High-Entropy-Alloy Nanoparticles for Electrocatalysis.

High-entropy-alloy nanoparticles (HEA NPs) exhibit promising potential in various catalytic applications, yet a robust synthesis strategy has been elusive. Here, we introduce a straightforward and universal method, involving the microexplosion of Leidenfrost droplets housing carbon black and metal salt precursors, to fabricate PtRhPdIrRu HEA NPs with a size of ∼2.3 nm. The accumulated pressure within the Leidenfrost droplet triggers an intense explosion within milliseconds, propelling the carbon support and metal salt rapidly into the hot solvent through explosive force. The exceptionally quick temperature rise ensures the coreduction of metal salts, and the dilute local concentration of metal ions limits the final size of the HEA NPs. Additionally, the explosion process can be fine-tuned by selecting different solvents, enabling the harvesting of diverse HEA NPs with superior electrocatalytic activity for alcohol electrooxidation and hydrogen electrocatalysis compared to commercial Pt (Pd) unitary catalysts.

Unlocking the Potential of Bi2S3-Derived Bi Nanoplates: Enhanced Catalytic Activity and Selectivity in Electrochemical and Photoelectrochemical CO2 Reduction to Formate.

Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO2 reduction reaction (CO2RR). However, an efficient CO2RR electrocatalyst doesn't ensure an effective co-catalyst on the semiconductor surface for photoelectrochemical CO2RR. Herein, Bi2S3 nanorods are synthesized and electrochemically reduced to Bi nanoplates that adhere to the substrates for application in the electrochemical and photoelectrochemical CO2RR. Compared with commercial-Bi, the Bi2S3-derived Bi (S-Bi) nanoplates on carbon paper exhibit superior electrocatalytic activity and selectivity for formate (HCOO-) in the electrochemical CO2RR, achieving a Faradaic efficiency exceeding 93%, with minimal H2 production over a wide potential range. This highly selective S-Bi catalyst is being employed on the Si photocathode to investigate the behavior of electrocatalysts during photoelectrochemical CO2RR. The strong adhesion of the S-Bi nanoplates to the Si nanowire substrate and their unique catalytic properties afford exceptional activity and selectivity for HCOO- under simulated solar irradiation. The selectivity observed in electrochemical CO2RR using the S-Bi catalyst correlates with that seen in the photoelectrochemical CO2RR system. Combined pulsed potential methods and theoretical analyses reveal stabilization of the OCHO* intermediate on the S-Bi catalyst under specific conditions, which is critical for developing efficient catalysts for CO2-to-HCOO- conversion.

Incorporation of Ag in Co9S8-Ni3S2 for Predominantly Enhanced Electrocatalytic Activities for Oxygen Evolution Reaction: A Combined Experimental and DFT Study.

Electrodeposition of abundant metals to fabricate efficient and durable electrodes play a viable role in advancing renewable electrochemical energy technologies. Herein, we deposit Co9S8-Ag-Ni3S2@NF onto nickel foam (NF) to form Co9S8-Ag-Ni3S2@NF as a highly efficient electrode for oxygen evolution reaction (OER). The electrochemical investigation verifies that the Co9S8-Ag-Ni3S2@NF electrode exhibits superior electrocatalytic activity toward OER because of its nanoflowers' open-pore morphology, reduced overpotential (η10 = 125 mV), smaller charge transfer resistance, long-term stability, and a synergistic effect between various components, which allows the reactants to be more easily absorbed and subsequently converted into gaseous products during the water electrolysis process. DFT calculation also reveals that the introduction of Ag (222) surface into the Co9S8 (440)-Ni3S2 (120) system increases the electronic density of states per unit cell of a system and significantly reduces the energy barriers of intermediates for OER, leading to enhanced electrocatalytic activity for OER. This study showcases the innovation of employing trimetallic nanomaterials immobilized on a conductive, continuous porous three-dimensional network formed on a nickel foam (NF) substrate as a highly efficient catalyst for OER.

Unveiling carcinogenic pollutant levels in environmental water samples through facile fabrication of gold nanoparticles on sulfur-doped graphitic carbon nitride

Extensive utilization of pesticides and herbicides to boost agricultural production increased the environmental health risks, which can be mitigate with the aid of highly sensitive detection systems. In this study, an electrochemical sensor for monitoring the carcinogenic pesticides in the environmental samples has been developed based on sulfur-doped graphitic-carbon nitride–gold nanoparticles (SCN-AuNPs) nanohybrid. Thermal polycondensation of melamine with thiourea followed by solvent exfoliation via ultrasonication leads to SCN formation and electroless deposition of AuNPs on SCN leads to SCN-AuNPs nanohybrid synthesis. The chemical composition, S-doping, and the morphology of the nanohybrid were confirmed by various microscopic and spectroscopic tools. The as-synthesized nanohybrid was fabricated with glassy carbon (GC) electrode for determining the carcinogenic hydrazine (HZ) and atrazine (ATZ) in field water samples. The present sensor exhibited superior electrocatalytic activity than GC/SCN and GC/AuNPs electrodes due to the synergism between SCN and AuNPs and the amperometric studies showed the good linear range of detection of 20 nM–0.5 mM and 500 nM–0.5 mM with the limit of detection of 0.22 and 69 nM (S/N = 3) and excellent sensitivity of 1173.5 and 13.96 μA mM−1 cm−2 towards HZ and ATZ, respectively. Ultimately, the present sensor is exploited in environmental samples for monitoring HZ and ATZ and the obtained results are validated with high-performance liquid chromatography (HPLC) technique. The excellent recovery percentage and close agreement with the results of HPLC analysis proved the practicability of the present sensor. In addition, the as-prepared materials were utilized for the photocatalytic degradation of ATZ and the SCN-AuNPs nanohybrid exhibited higher photocatalytic activity with the removal efficiency of 93.6% at 90 min. Finally, the degradation mechanism was investigated and discussed.

Seamless construction of self-supporting nanoporous FeCoZn alloy as one highly efficient electrocatalyst for oxygen evolution reaction in alkaline media

Exploring high-efficient and economical electrocatalyst for oxygen evolution reaction (OER) is critical for the electrocatalytic water splitting technology to hydrogen production. Herein, we report a hierarchical nanoporous FeCoZn alloys with different Fe/Co atomic ratios in-situ constructed on bimodal porous NiZn intermetallic and Ni heterojunction over nickel foam (FeCoZn/NF) through a scalable electroplating-annealing-etching strategy. The synergistic effect between multi-elements, multiple interface coupling, and self-supporting seamless porous architecture is beneficial for enhancing the number of active sites but also promoting efficient mass transport and electron transfer. FeCoZn/NF exhibits the superior electrocatalytic activity toward OER with a low overpotential of 440 mV at 1004 mA cm−2 and small Tafel slope of 84.8 mV dec−1. The as-made sample also shows exceptional long-term catalytic stability in alkaline media with 1.0 M KOH of remained under the overpotential of 350 mV for 100 h. Besides, the combined FeCoZn/NF and Pt/C/NF for overall water splitting needs the cell potential of 1.481 V at 10 mA cm−2, along with long-term stability. This work provides implications for the design and preparation of highly active non-noble metal-based multiple alloy electrocatalysts.

Transition-Metal Porphyrin-Based MOFs In Situ-Derived Hybrid Catalysts for Electrocatalytic CO2 Reduction.

Excellent electrocatalytic CO2 reduction reaction activity has been demonstrated by transition metals and nitrogen-codoped carbon (M-N-C) catalysts, especially for transition-metal porphyrin (MTPP)-based catalysts. In this work, we propose to use one-step low-temperature pyrolysis of the isostructural MTPP-based metal-organic frameworks (MOFs) and electrochemical in situ reduction strategies to obtain a series of hybrid catalysts of Co nanoparticles (Co NPs) and MTPP, named Co NPs/MTPP (M = Fe, Co, and Ni). The in situ introduction of Co NPs can efficiently enhance the electrocatalytic ability of MTPP (M = Fe, Co, and Ni) to convert CO2 to CO, particularly for FeTPP. Co NPs/FeTPP endowed a high CO faradaic efficiency (FECOmax = 95.5%) in the H cell, and the FECO > 90.0% is in the broad potential range of -0.72 to -1.22 VRHE. In addition, the Co NPs/FeTPP achieved 145.4 mA cm-2 at a lower potential of -0.70 VRHE with an FECO of 94.7%, and the CO partial currents increased quickly to reach 202.2 mA cm-2 at -0.80 VRHE with an FECO of 91.6% in the flow cell. It is confirmed that Co NPs are necessary for hybrid catalysts to get superior electrocatalytic activity; Co NPs also can accelerate H2O dissociation and boost the proton supply capacity to hasten the proton-coupled electron-transfer process, effectively adjusting the adsorption strength of the reaction intermediates.

Construction of Cu Single‐Atom Catalysts by Taking Spatial‐Confinement and Chemical‐Anchoring Effect of Hyperbranched Phthalocyanine Copper for Efficient Oxygen Reduction Reaction

AbstractAtomically dispersed nonprecious metal‐based catalysts have been considered as the most promising alternatives to Pt‐based catalysts since their excellent catalytic activities and almost 100 % atom utilization in oxygen reduction reaction. However, the agglomeration of metal atoms is unavoidable during pyrolysis process, thus leads to the decrease of electrocatalytic performance. Herein, hyperbranched phthalocyanine copper (HCuPc) wrapping nano‐silica is synthesized via in situ polymerization and served as precursor for preparing atomically dispersed Cu−N−C electrocatalysts. Owing to the confinement effect of chemical‐anchoring and spatial‐hindrance, the migration and agglomeration of Cu atoms are restricted in carbonization process. The aberration‐corrected high‐angle annular dark‐field scanning transmission electron microscopy and X‐ray photoelectron spectroscopy (XPS) are performed to confirm the atomically dispersed of as‐synthesized catalyst, which is labelled as HCu−N−C/SiO2. In addition, the HCu−N−C/SiO2 possess superior ORR electrocatalytic activities with a half‐wave potential of 0.874 V vs RHE and a limiting current density of 5.7 mA cm−2. The zinc‐air batteries assembled with HCu−N−C/SiO2 catalyst exhibit a high specific capacity of 789 mAh g−1 as well as a maximum discharge power density of 176 mW cm−2. This work proves that hyperbranched phthalocyanine structure could be a useful confined framework to the fabrication of singles‐atom catalysts.

Synergistic Sb2S3-NiS2 heterostructure: A robust electrocatalyst for electrochemical sensing of Hg (II), As (III) ions and carbendazim fungicide

We developed a novel modified electrode based on Sb2S3-NiS2 heterostructure for the electrochemical detection of carbendazim, mercury (Hg2+), and arsenic (As3+). XRD, FESEM, HRTEM, and XPS characterization techniques were employed to confirm the formation of Sb2S3-NiS2 heterostructures. In comparison to other electrodes, the Sb2S3-NiS2 modified electrode has a strong electrocatalytic performance towards carbendazim, Hg2+, and As3+ detection. The Sb2S3-NiS2 nanocomposite's superior electrocatalytic activity is ascribed to its high conductivity, charge capacitance, synergistic effect, substantial number of active sites, and metal trap centres. Electrochemical studies such as cyclic voltammetry, LSV, and DPV depict excellent sensing capacity of Sb2S3-NiS2 for carbendazim, Hg2+, and As3+ with an ultralow detection limit calculated as 0.42 nM, 8.3 nM, and 92 nM, respectively. This is much below the upper limit established by the World Health Organization and the US Environmental Protection Agency. The chronoamperometry response and reusability up to weeks suggest excellent and superior stability. Furthermore, the modified electrode successfully detected carbendazim in real samples of apple and tomato juices and Hg2+ ions in the water of the Dal Lake. As far as we know, this is the first report on the Sb2S3-NiS2 heterostructure's electrocatalytic capability. Hopefully, this study will provide new insight into the future fabrication and development of novel electrocatalyst materials.