Superior Electrocatalytic Activity Research Articles

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.

Red Carbon Mediated Formation of Cu2O Clusters Dispersed on the Oxocarbon Framework by Fehling's Route and their Use for the Nitrate Electroreduction in Acidic Conditions.

The oligomers of carbon suboxide, known as red carbon, exhibit a highly conjugated structure and semiconducting properties. Upon mild heat treatment, it transforms into a carbonaceous framework rich in oxygen surface terminations, called oxocarbon. In this study, the abundant oxygen functionalities are harnessed as anchors to create oxocarbon-supported nanohybrid electrocatalysts. Starting with single atomic Cu (II) strongly coordinated to oxygen atoms on red carbon, the Fehling reaction leads to the formation of Cu2O clusters. Simultaneously, a covalent oxocarbon framework emerges via cross-linking, providing robust support for Cu2O clusters. Notably, the oxocarbon support effectively stabilizes Cu2O clusters of very small size, ensuring their high durability in acidic conditions and the presence of ammonia. The synthesized material exhibits a superior electrocatalytic activity for nitrate reduction under acidic electrolyte conditions, with a high yield rate of ammonium (NH4 +) at 3.31mmolh-1mgcat -1 and a Faradaic efficiency of 92.5% at a potential of -0.4V (vs RHE).

Electrodeposited CrMnFeCoNi Oxy-carbide film and effect of selective dissolution of Cr on oxygen evolution reaction

High entropy compounds were proven to exhibit excellent catalytic activity. Here, a series of amorphous CrMnFeCoNi Oxy-carbide films were successfully synthesized by one-step electrodeposition. As demonstrated, the film presented superior electrocatalytic activity for oxygen evolution reaction (OER) with an overpotential of 295 mV at a current density of 10 mA/cm2. Uniquely, selective dissolution of Chromium (Cr) was observed, which increased the catalytic activity and showed high stability under a large current density of up to 400 mA/cm2. Cr dissolution not only increased the surface area but also improved the conductivity due to newly formed metal-metal bonding, promoting electron transfer and improving OER performance. As revealed by density functional theory (DFT) calculations, Cr-dissolution mediates the bonding of OER intermediates over surface active sites and ultimately reduces OER overpotential. The one-step electrodeposition method and the micro-dissolution mechanism provided a potential way to design and prepare high entropy compound electrodes, aiming to achieve efficient water electrolysis.

Hydrothermal synthesis of nickel vanadate (Ni2V2O7) microspheres as a catalyst for high-performance supercapacitor and water-splitting applications

In this work, the hydrothermal method was employed to synthesize the nickel vanadate microspheres (NVO MSs), an effective catalyst for supercapacitor and water-splitting applications. Specifically, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and Brunauer-Emmett-Teller (BET) were used to examine the crystal structure, surface morphology, functional group identification, the stretching-bending vibration of the N–V–O group, and the specific surface area respectively. Additionally, this paper reports the electrochemical aspects of NVO MSs in various concentrations of KOH electrolyte using nickel foam (NF) as a current collector. As a result, the NVO-NF 1 electrode exhibited excellent electrochemical activity with a higher specific capacitance (Cs) and capacity (Csp) of 959 F/g and 119 mAh/g at a current density of 5 mA/g respectively. Moreover, the NVO-NF 1 electrode delivers maximum energy (Ed) and power density (Pd) of 26 Wh/kg and 1100 W/kg and excellent stability with 90 % retention after 4000 CV cycles. In the asymmetric liquid state device (ASC), the NVO-NF acts as a cathode, and activated carbon (AC) as a anode materials respectively. Furthermore, the fabricated ASC device reveals maximum Ed and Pd of 47 Wh/kg and 2300 W/kg at 5 mA/g and also demonstrated superior stability over 5000 cycles. Furthermore, the significant finding of the NVO-NF 1 electrodes reveals superior electrocatalytic activities such as the lowest value of overpotential (234 mV), with the sufficient Tafel slope (73 mV/dec), as well as the maximum electrochemical active surface area (670.5 cm2) in 1 M KOH at 10 mA/cm2 respectively. As a result, better performance of the NVO-based MSs in 1 M KOH electrolyte was effectively applied to power effective electrodes for energy storage and water-splitting.

N-doped hollow carbon nanospheres embedded in N-doped graphene loaded with palladium nanoparticles as an efficient electrocatalyst for formic acid oxidation

Efficient electrocatalysts with a low cost, high activity and good durability play a crucial role in the use of direct formic acid fuel cells. Pd nanoparticles supported on N-doped hollow carbon nanospheres (NHCNs) embedded in an assembly of N-doped graphene (NG) with a three-dimensional (3D) porous structure by a simple and economical method were investigated as direct formic acid fuel cell catalysts. Because of the unique porous configuration of interconnected layers doped with nitrogen atoms, the Pd/NHCN@NG catalyst with Pd nanoparticles has a large catalytic active surface area, superior electrocatalytic activity, a high steady-state current density, and a strong resistance to CO poisoning, far surpassing those of conventional Pd/C, Pd/NG, and Pd/NHCN catalysts for formic acid electrooxidation. When the HCN/GO mass ratio was 1:1, the Pd/NHCN@NG catalyst had an outstanding performance in the catalytic oxidation of formic acid, with an activity 4.21 times that of Pd/C. This work indicates a way to produce superior carbon-based support materials for electrocatalysts, which will be beneficial for the development of fuel cells.

Degradation mechanism of methylene blue by heterogenous electro-Fenton with CeO2/rGO composite cathode

The noble materials have been regarded as the best catalysts for electro-generating H2O2 in electro-Fenton (EF) process, but their high cost is daunting. Herein, a noble-metal-free catalyst of CeO2/reduced graphene oxide (CeO2/rGO) was prepared for electro-generating H2O2 in this study. Due to a synergistic effect between the excellent electronic mobility of CeO2 and the unique interconnected electrical transmission channels of rGO, the CeO2/rGO composite exhibited superior electrocatalytic activity than CeO2 and rGO towards the electro-generation of H2O2. In EF experiments, the degradation rate constant of methylene blue (MB) at the CeO2/rGO cathode (0.025 min–1) was 2.27 times and 2.78 times that of CeO2 (0.011 min–1) and rGO (0.009 min–1), respectively. The investigation of reaction mechanism in EF process showed that the •OH radical was the major contributor, while the •O2– radical played an important role but was not the primary active species. In addition, the vulnerable sites and the possible degradation pathways of MB in EF process were proposed according to the density functional theory (DFT) calculation and experimental results of liquid chromatography-mass spectrometry.

Earthworm-Inspired Co/Co3O4/CoF2@NSC Nanofibrous Electrocatalyst with Confined Channels for Enhanced ORR/OER Performance.

The rational construction of highly active and durable oxygen-reactive electrocatalysts for oxygen reduction/evolution reaction (ORR/OER) plays a critical role in rechargeable metal-air batteries. It is pivotal to achieve optimal utilization of electrocatalytically active sites and valid control of the high specific internal surface area. Inspiration for designing electrocatalysts can come from nature, as it is full of precisely manipulated and highly efficient structures. Herein, inspired by earthworms fertilizing soil, a 3D carbon nanofibrous electrocatalyst with multiple interconnected nanoconfined channels, cobalt-based heterojunction active particles and enriched N, S heteroatoms (Co/Co3O4/CoF2@NSC with confined channels) is rationally designed, showing superior bifunctional electrocatalytic activity in alkaline electrolyte, even outperforming that of benchmark Pt/C-RuO2 catalyst. This work demonstrates a new method for porous structural regulation, in which the internal confined channels within the nanofibers are controllably formed by the spontaneous migration of cobalt-based nanoparticles under a CO2 atmosphere. Theoretical analysis reveals that constructing Co/Co3O4/CoF2@NSC electrocatalyst with confined channels can greatly adjust the electron distribution, effectively lower the reaction barrier of inter-mediate and reduce the OER/ORR overpotential. This work introduces a novel and nature-inspired strategy for designing efficient bifunctional electrocatalysts with well-designed architectures.

Facile Fabrication of an SnSx‐SnO2‐Decorated Cobalt Sulfide Film as an Effective Counter Electrode for Dye‐Sensitized Solar Cells

AbstractMetal sulfide stands out as one of the novel and promising platinum‐free counter electrode (CE) materials for dye‐sensitized solar cells (DSSCs). In this work, SnSx‐SnO2‐decorated CoSx films were designed and synthesized by a low‐temperature fabrication process. The small clusters of nanoparticles create a large amount of catalytic active sites, resulting in superior electrocatalytic activity for triiodide reduction. The DSSC with SnSx‐SnO2‐decorated CoSx film has achieved an impressive power conversion efficiency of 4.57 %, which is close to the efficiency of the DSSC with platinum CE (4.82 %). Furthermore, regarding the attenuation of the photovoltaic performance for the DSSC with SnSx‐SnO2‐decorated CoSx film, negligible change was observed after a prolonged storage under ambient condition for five days. Therefore, it is worthwhile to expect the explorations of novel fabricate technique for synthesizing cost‐effective metal sulfide films with long‐term stability in DSSCs.

Magnetic reinforcement of electrocatalytic HER performance on Keplerate polyoxomolybdate-derived multi-interfacial FeMo/Mo2C@C catalyst

Electrocatalysis is a promising approach for sustainable hydrogen generation, and the exploration of effective electrocatalysts for hydrogen evolution reactions (HER) is of great significance for exploiting and utilizing renewable energy. Herein, the magnetic FeMo/Mo2C@C composites with multi-heterostructure interfaces and hierarchical structure are first designed and fabricated via molybdenum blue preassembly strategy by using Keplerate polyoxomolybdate {Mo72Fe30} and melamine as precursors. Benefiting from its unique characteristics, FeMo/Mo2C@C catalyst exhibits superior HER electrocatalytic activity than pure Mo2C@C. Interestingly, the optimized FeMo/Mo2C@C presents the HER magnetic reinforcement by simply applying an magnetic field, characteristic of 97 mV@10 mA cm–2, 201 mV@50 mA cm–2, and a robust durability for more than 18 h, which are 120 and 85 mV less than that of FeMo/Mo2C@C without magnetization, and greatly lower than comparative Mo2C@C catalyst (272 mV@10 mA cm–2 and 396 mV@50 mA cm–2). This may be attributed to that the FeMo/Mo2C@C can afford fast electrons transmitting from electrode to active sites during HER process when imposing an external magnetic field. This work offers a novel design direction to develop magnetic transition metal based-materials for electrochemical applications and paves a new way to utilize the magnetic enhancement to further improve the hydrogen evolution performance.

Interface Engineering Overall Seawater Splitting of Self-Supporting CeOx@NiCo2O4 Arrays.

Exploring advanced electrocatalysts for overall seawater splitting is of great significance for large-scale green hydrogen production in which interface engineering has been considered as an effective strategy to enhance the intrinsic activities of the electrocatalysts. In this work, CeOx-modified NiCo2O4 nanoneedle arrays are designed and constructed in situ grown on Ni foam (NF) through a facile two-step synthesis method. Density functional theory calculations reveal that the strong interaction between CeOx and NiCo2O4 can regulate the electronic states of metal surfaces and optimize the electronic structures of the materials, essentially improving the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) properties. Specifically, in alkaline electrolytes, CeOx@NiCo2O4/NF exhibits superior electrocatalytic activities and stabilities, requiring overpotentials of 238 mV for the OER and 144 mV for the HER to achieve a current density of 10 mA cm-2. When applied to a simulated seawater splitting device, the CeOx@NiCo2O4/NF also maintains a battery voltage of 1.66 V to reach 10 mA cm-2 and exhibits good stability for over 60 h, with high faradic efficiencies (FEs) close to 100% for both the OER and HER.

Balancing electron transfer and intermediate adsorption ability of metallic Ni-Fe-RE-P bifunctional catalysts via 4f-2p-3d electron interaction for enhanced water splitting

Balancing electron transfer and intermediate adsorption ability of bifunctional catalysts via tailoring electronic structures is crucial for green hydrogen production, while it still remains challenging due to lacking efficient strategies. Herein, one efficient and universal strategy is developed to greatly regulate electronic structures of the metallic Ni-Fe-P catalysts via in-situ introducing the rare earth (RE) atoms (Ni-Fe-RE-P, RE = La, Ce, Pr, and Nd). Accordingly, the as-prepared optimal Ni-Fe-Ce-P/CC self-supported bifunctional electrodes exhibited superior electrocatalytic activity and excellent stability with the low overpotentials of 247 and 331 mV at 100 mA cm−2 for HER and OER, respectively. In the assembled electrolyzer, the Ni-Fe-Ce-P/CC as bifunctional electrodes displayed low operation potential of 1.49 V to achieve a current density of 10 mA cm−2, and the catalytic performance can be maintained for 100 h. Experimental results combined with density functional theory (DFT) calculation reveal that Ce doping leads to electron decentralization and crystal structure distortion, which can tailor the band structures and d-band center of Ni-Fe-P, further increasing conductivity and optimizing intermediate adsorption energy. Our work not only proposes a valuable strategy to regulate the electron transfer and intermediate adsorption of electrocatalysts via RE atoms doping, but also provides a deep understanding of regulation mechanism of metallic electrocatalysts for enhanced water splitting.