Electronic Structure Of Active Site Research Articles

Porous TiN-based ceramic electrode with N-modified Co-based Nanorods/TiN heterointerfaces for efficient overall water splitting

The development of high-performance electrocatalytic electrodes for overall water splitting is a crucial issue to realize renewable hydrogen production. This paper presents the in situ growth of N-modified Co-based nanorods on porous TiN ceramic membranes using the hydrothermal method and thermal NH3 treatment, resulting in a novel self-supported electrocatalytic electrode with abundant heterointerfaces, denoted as NCTN-x-y (x: nitridation temperature; y: nitridation time). In the alkaline medium (1 M KOH), the NCTN-350-2 electrode displays the best hydrogen evolution reaction (HER) activity (ƞ10 = 66 mV), and the NCTN-250-3 electrode manifests the best oxygen evolution reaction (OER) performance (ƞ10 = 270 mV). Accordingly, these two electrodes comprise an electrolyzer, which features a current density of 10 mA cm−2 at a low cell voltage of 1.63 V. The good electrocatalytic performance can be attributed to the abundant heterointerfaces formed between the porous TiN ceramic membrane and the N-modified Co-based nanorods, in conjunction with the hierarchical pore structure of the TiN ceramic membrane. Theoretical calculations identify that the construction of heterointerfaces modulates the electronic structure of active sites, thereby promoting the dissociation of H2O, optimizing the H* adsorption energy (ΔGH*), and accelerating the reaction kinetics, which ultimately improve the electrocatalytic activity of electrode.

Modulating electronic structure of active sites on iron-based nanoparticles enhances peroxymonosulfate activation

Herein, iron-based nanoparticle catalysts with heteroatoms anchored on nitrogen-doped carbon layers were constructed and applied to peroxymonosulfate (PMS) activation for antibiotic degradation. Results showed that S doping was beneficial to PMS activation, while P doping reduced the activation efficiency. The S-doped catalysts achieved 100% removal of sulfamethoxazole (SMX) within 15 min with a normalized rate constant of 130.4 min−1 M−1. Electron paramagnetic resonance and scavenging tests proved that high-valent iron-oxo species (HV-FeO) and singlet oxygen (1O2) mediated non-radical oxidation dominated the SMX degradation. Theoretical calculations and experiments elucidated that the electron-rich S atom donated electrons during PMS activation, which changed the valence state of Fe and enhanced the adsorption energy to PMS (Eads = −11.219 eV), resulting in excellent catalytic activity. This work elucidated the effects of heteroatoms on the electronic structure of active site in nanoparticles and provided guidance for the development of advanced catalysts for PMS activation.

Ni─Co─O─S Derived Catalysts on Hierarchical N-doped Carbon Supports with Strong Interfacial Interactions for Improved Hybrid Water Splitting Performance.

Simultaneously improving electrochemical activity and stability is a long-term goal for water splitting. Herein, hierarchical N-doped carbon nanotubes on carbon nanowires derived from PPy are grown on carbon cloth, serving as a support for NiCo oxides/sulfides. The hierarchical electrodes annealed in N2 or H2/N2 display improved intrinsic activity and stability for hydrogen evolution reaction (HER) and glucose oxidation reaction. Compared with Pt/C||Ir/C in alkaline media, the glucose electrolysis assembled with electrodes exhibits a cell voltage of 1.38V at 10mAcm-2, durability for >12h at 50mAcm-2, and resistance to glucose/gluconic acid poisoning. In addition, electrocatalysts can also be applied in ethanol oxidation reactions. Systematic characterizations reveal the strong interactions between NiCo and N-doped carbon support-induced partial charge transfer at the interface and regulate the local electronic structure of active sites. Density functional theory calculations demonstrate that the synergistic effect between N-doped carbon supports, metallic NiCo, and NiCo oxides/sulfides optimize the adsorption energy of H2O and the H* free energy for HER. The energy barrier of the dehydrogenation of glucose effectively decreased. This work will attract attention to the role of metal-support interactions in enhancing the intrinsic activity and stability of electrocatalysts.

Coordination Environment Engineering to Regulate the Adsorption Strength of Intermediates in Single Atom Catalysts for High-performance CO2 Reaction Reduction.

The modulation of the coordination environment of single atom catalysts (SACs) plays a vital role in promoting CO2 reduction reaction (CO2 RR). Herein, N or B doped Fe-embedded graphyne (Fe-GY), Fe-nXGYm (n = 1, 2, 3; X = N, B; m = 1, 2, 3), are employed as probes to reveal the effect of the coordination environment engineering on CO2 RR performance via heteroatom doping in SACs. The results show that the doping position and number of N or B in Fe-GY significantly affects catalyst activity and CO2 RR product selectivity. In comparison, Fe-1NGY exhibits high-performance CO2 RR to CH4 with a low limiting potential of -0.17V, and Fe-2NGY3 is demonstrated as an excellent CO2 RR electrocatalyst for producing HCOOH with a low limiting potential of -0.16V. With applied potential, Fe-GY, Fe-1NGY, and Fe-2NGY3 exhibit significant advantages in CO2 RR to CH4 while hydrogen evolution reaction is inhibited. The intrinsic essence analysis illustrates that heteroatom doping modulates the electronic structure of active sites and regulates the adsorption strength of the intermediates, thereby rendering a favorable coordination environment for CO2 RR. This work highlights Fe-nXGYm as outstanding SACs for CO2 RR, and provides an in-depth insight into the intrinsic essence of the promotion effect from heteroatom doping.

Constructing NiSe2/MoSe2 Mott–Schottky Heterojunctions Onto N‐doped Brain Coral‐Carbon Spheres by Phase Separation Strategies for Advanced Energy Conversion Applications

AbstractConstructing Mott–Schottky heterojunctions in nanohybrids is an effective strategy for facilitating electron transfer and optimizing the electronic structure of active sites; however, challenges remain. Herein, a selenium‐induced phase separation strategy is proposed and successfully construct NiSe2/MoSe2 Mott–Schottky heterojunctions on N‐doped brain coral carbon nanospheres (N‐BCCSs). Owing to built‐in electric fields, optimized electronic density, and unique nanoflake/sphere structures, the designed NiSe2/MoSe2@N‐BCCSs carbon‐based Mott–Schottky catalysts achieved satisfactory electrocatalytic performance. When serving as a counter electrode for the triiodide reduction reaction (IRR), a power conversion efficiency of 8.49% is obtained, which outperformed that of conventional Pt electrodes (7.80%). When the NiSe2/MoSe2@N‐BCCSs are used as electrocatalysts for the hydrogen evolution reaction (HER), their overpotential (η10) is as low as 119 mV, which is significantly better than that of other transition‐metal selenides. This research demonstrates a new concept for constructing Mott–Schottky heterojunctions and provides a new direction for investigating multifunctional carbon‐based composites.

Immobilizing Bimetallic RuCo Nanoalloys on Few-Layered MXene as a Robust Bifunctional Electrocatalyst for Overall Water Splitting.

Doping Co atoms into Ru lattices can tune the electronic structure of active sites, and the conductive MXene can adjust the electrical conductivity of catalysts, which are both favorable for improving the electrocatalytic activity of the catalyst for water splitting. Here, ruthenium-cobalt bimetallic nanoalloys coupled with exfoliated Ti3 C2 Tx MXene (RuCo-Ti3 C2 Tx ) have been constructed by ice-templated and thermal activation. Due to the strong interaction between the RuCo nanoalloys and conductive MXene, RuCo-Ti3 C2 Tx not only exhibits an excellent hydrogen evolution reaction (HER) performance with a low overpotential and Tafel slope (60 mV, 34.8 mV dec-1 in 0.5 M H2 SO4 and 52 mV, 38.7 mV dec-1 in 1 M KOH), but also good oxygen evolution reaction (OER) performance in an alkaline electrolyte (266 mV, 111.1 mV dec-1 in 1 M KOH). The assembled RuCo-Ti3 C2 Tx ||RuCo-Ti3 C2 Tx electrolyzer requires a lower potential (1.56 V) than does the Pt/C||RuO2 electrolyzer at 10 mA cm-2 . A boosted catalytic HER activity from immobilizing the RuCo nanoalloys on MXene was unveiled by density functional theory calculations. This study provides a feasible and efficient strategy for developing MXene-based catalysts for overall water splitting.

Overlooked role of void-nanoconfined effect in emerging pollutant degradation: Modulating the electronic structure of active sites to accelerate catalytic oxidation

The efficient removal of emerging pollutant from water is the ultimate frontiers of advanced oxidation processes (AOPs), yet it is challenging to obtain higher catalytic activity and oxidation rate. Herein, a sustainable solution was proposed by optimizing the curvature of confined structure to modulate the electronic state of the active sites in nanochannels for improving the catalytic activity. In addition, the confined effect can enhance the oxidation rate by shorting the mass transfer of active species and pollutants. A void-nanoconfined nanoreactor was prepared by loading Fe2O3 into the nanochannels (<5 nm) of the hollow carbon sphere. An enhancement of 3 orders of magnitude was obtained in the degradation rate constant of void-nanoconfined catalytic system toward sulfamethoxazole (SMX) (6.25 min−1) compared with the non-confined system. The kinetics enhancement was attributed to the larger electron potential difference between the outer and inner nanochannel caused by the curvature increase of carbon sphere, accelerating the electron transfer, so that the energy barrier of SMX degradation reaction was reduced by 31 kcal/mol with the assistance of confinement energy. Importantly, the NC-IN/PDS system exhibited outstanding removal efficiency for the actual river water using a continuous flow reactor. This work provides a new insight into designing an efficient and stable catalytic nanoreactor, enriching the domain of advanced wastewater treatment strategies.

Anionic Regulation and Heteroatom Doping of Ni‐Based Electrocatalysts to Boost Biomass Valorization Coupled with Hydrogen Production

AbstractElectrocatalytic biomass valorization coupled with hydrogen production provides an efficient and economical way to achieve a zero‐carbon economy. Ni‐based electrocatalysts are promising candidates due to their intrinsic redox capabilities, but the rational design of active Ni site coordination is still a huge challenge. Herein, the combined strategies of surface reconstruction and heteroatom doping are adopted to modify Ni3S2 pre‐catalysts and the obtained bimetallic catalyst exhibits superior electrocatalytic performance toward 5‐hydroxymethylfurfural (HMF) oxidation to 2,5‐furanedicarboxylic acid (FDCA). Specifically, the oxysulfide‐coordinated amorphous NiOOH (NiOOH‐SOx) active phase is in situ constructed following the anionic regulation mechanism, which endows numerous defects and unsaturated sites for anodic HMF oxidation. Cu heteroatom doping further modulates the electronic structure of active sites with abundant Lewis acidic sites, offering advanced capability for HMF adsorption. Several operando characterization techniques (in situ Raman, infrared, and electrochemical impedance spectroscopies) are performed to disclose the reaction pathway and structure‐activity‐potential relationship. Theoretical results further demonstrate that Cu doping and oxyanionic regulation effectively modulate the local coordination environment of Ni sites and correspondingly tailor the intermediate adsorption behavior and then promote the reaction kinetics. Moreover, a two‐electrode system is assembled to pair HMF oxidation with cathode hydrogen production, demonstrating better energy conversion efficiency.

Ni3S4/FeNi2S4 heterostructure-embedded metal-organic framework-derived nanosheets interconnected by carbon nanotubes for boosting oxygen evolution reaction

The efficiency of electrolytic water splitting is hampered by the slow kinetics of the oxygen evolution reaction (OER). Addressing this challenge, we present a novel catalyst with rich Ni3S4/FeNi2S4 heterostructures anchored metal-organic framework-derived nanosheets interconnected by carbon nanotubes (NiFe–S@CNT). The NiFe–S@CNT electrocatalyst shows an ultralow overpotential of 246 mV at a current density of 10 mA/cm2 (η10), surpassing the benchmark RuO2 (η10 = 291 mV) as well as many reported sulfide electrocatalysts. The strong heterointerface interaction between Ni3S4 and FeNi2S4 induce synergistic effects, modifying the electronic structure of active sites and generating a large number of lattice defects. Additionally, the carbon nanotubes skeleton facilitates efficient electron transfer and enhances electrical conductivity during the catalytic process. Moreover, the metal-organic framework derivative inherits a porous structure, aiding in electrolyte penetration and efficient bubble release. This study provides a facile and scalable strategy to develop nonprecious transition-metal-based OER catalysts with abundant heterointerfaces and active sites for efficient water splitting.

In-depth investigation on the influence of iron impurity on the oxygen evolution performance of iron-based catalysts

It is well-known that Fe3+ impurities in the electrolyte can significantly promote the oxygen evolution reaction (OER) activity of Co-based and Ni-based electrocatalysts. However, it is not clear if they work for single-metal Fe-based catalysts. Here, we systematically investigate the influence of Fe3+ ions in the electrolyte on the OER activity of core-shell FeOx@C catalytic system. We find that the absorbed Fe3+ can induce the generation of surface oxygen vacancies and regulate the electronic structure of active sites, thus increasing the OER kinetics and decreasing the energy barrier. Combining with in-situ Raman and ex-situ X-ray photoelectron spectroscopy (XPS) analysis, we disclose that Fe4+ species is the active species for the OER and positively correlate the characteristic content of the high-valence Fe species and OER activity.

Constructing heterostructure of WP/WP2 to enhance catalytic activity and stability toward hydrogen generation

Transition metal phosphides (TMPs) have been identified as potential electrocatalysts for the hydrogen evolution reaction (HER) due to their unique structural and electronic properties. However, TMPs have not yet achieved the desired HER performance, and further improvements are required. Herein, we fabricate heterostructured tungsten phosphide/tungsten diphosphide (WP/WP2) composite microrods grown on carbon cloth (WP/WP2/CC) as an efficient self-supported electrocatalyst, which is proven to be highly efficient and stable for the HER. Various experimental results and density functional theory calculations reveal that the formation of WP/WP2 heterostructures can regulate the electronic structure of active sites and optimize hydrogen adsorption free energy on active sites, which accelerates the electron transfer and boosts the HER performance to WP/WP2/CC. By tuning the phosphidation temperatures, the optimized WP/WP2/CC electrocatalyst shows a superior HER performance with low overpotentials of 92 mV and 146 mV at 10 mA cm−2 in 0.5 M H2SO4 and 1.0 M KOH solutions. Meanwhile, it maintains a stable activity at 100 and 150 mV for at least 12 h in 0.5 M H2SO4 and 1.0 M KOH media, respectively. This study demonstrates that the construction of heterostructures can serve as an efficient strategy to improve the electrocatalytic performance of metal phosphide-based electrocatalysts.

Enhancing Hydrogen Peroxide Synthesis through Coordination Engineering of Single-Atom Catalysts in the Oxygen Reduction Reaction: A Review

Hydrogen peroxide (H2O2) is an important chemical with a diverse array of applications. However, the existing scenario of centralized high-concentration production is in contrast with the demand for low-concentration decentralized production. In this context, the on-site green and efficient two-electron oxygen reduction reaction (ORR) for H2O2 production has developed into a promising synthetic approach. The development of low-cost, highly active, and durable advanced catalysts is the core requirement for realizing this approach. In recent years, single-atom catalysts (SACs) have become a research hotspot owing to their maximum atom utilization efficiency, tunable electronic structure, and exceptional catalytic performance. The coordination engineering of SACs is one of the key strategies to unlock their full potential for electrocatalytic H2O2 synthesis and holds significant research value. Despite considerable efforts, precisely controlling the electronic structure of active sites in SACs remains challenging. Therefore, this review summarizes the latest progress in coordination engineering strategies for SACs, aiming to elucidate the relevance between structure and performance. Our goal is to provide valuable guidance and insights to aid in the design and development of high-performance SACs for electrocatalytic H2O2 synthesis.

Electronic Structure Regulation and Surface Reconstruction of Iron Diselenide for Enhanced Oxygen Evolution Activity.

Regulating the electronic structure of active sites and monitoring the evolution of the active component is essential to improve the intrinsic activity of catalysts for electrochemical reactions. Herein, a highly efficient pre-electrocatalyst of iron diselenide with rich Se vacancies achieved by phosphorus doping (denoted as P-FeSe2 ) for oxygen evolution reaction (OER) is reported. Systematically experimental and theoretical results show that the formed Se vacancies with phosphorus doping can synergistically modulate the electronic structure of FeSe2 and facilitate OER kinetics with the resulting enhanced electrical conductivity and electrochemical surface area. Importantly, the in situ formed FeOOH species on the surface of the P-FeSe2 nanorods (denoted as P-FeOOH(Se)) during the OER process acts as an active component to efficiently catalyze OER and exhibits a low overpotential of 217 mV to reach 10 mA cm-2 with good durability. Promisingly, an alkaline electrolyzer assembled with P-FeOOH(Se) and Pt/C electrodes requires an ultra-low cell voltage of 1.50 V at 10 mA cm-2 for overall water splitting, which is superior to the RuO2 || Pt/C counterpart and most of the state-of-the-art electrolyzers, demonstrating the high potential of the fabricated electrocatalyst by P doping strategy to explore more highly efficient selenide-based catalysts for various reactions.

Pd@PtRuNi core–shell nanowires as oxygen reduction electrocatalysts

Fuel cells, as the alternative to fossil energy, have engaged widespread attention by reason of the high conversion efficiency from the chemical energy to the electric energy combined with low pollution emissions. The cathodic ORR catalysts with excellent performance and cost-effectiveness are the dominant point towards the massive development of fuel cells. Here, our group select the Pd NWs as the template and construct the Pd@PtRuNi core–shell bilayer nanostructure to expand platinum atom utilization. Pd@PtRuNi bilayer core–shell NWs unfold elevated mass activity of at 0.9 V versus RHE in alkaline media, 2.03- and 6.23-fold of pristine Pd NWs and benchmark commercial Pt/C, respectively. Meanwhile, the cyclic stability tests reveal the excellent durability of Pd@PtRuNi NWs, whose mass activity is only 13.58% degradation after accelerated durability tests. The catalytic activity and durability towards ORR are better than the U.S. 2025 DOE target ( and less than 40% activity attenuation at 0.9 V after 30 000 potential cycles). The elevated catalytic properties can be traceable to the synergism between the ligand effect of Ni and Ru and one-dimensional structure superiority, which optimizes the electronic structure of active sites, promotes the charge transfer and restrains the agglomeration and detachment.

Enhancing Electrochemical CO2 Reduction on Perovskite Oxide for Solid Oxide Electrolysis Cells through In Situ A-Site Deficiencies and Surface Carbonate Deposition Induced by Lithium Cation Doping and Exsolution.

Solid oxide electrolysis cells (SOECs) hold enormous potential for efficient conversion of CO2 to CO at low cost and high reaction kinetics. The identification of active cathodes is highly desirable to promote the SOEC's performance. This study explores a lithium-doped perovskite La0.6- x Lix Sr0.4 Co0.7 Mn0.3 O3-δ (x = 0, 0.025 0.05, and 0.10) material with in situ generated A-site deficiency and surface carbonate as SOEC cathodes for CO2 reduction. The experimental results indicate that the SOEC with the La0.55 Li0.05 Sr0.4 Co0.7 Mn0.3 O3-δ cathode exhibits a current density of 0.991 A cm-2 at 1.5V/800°C, which is an improvement of ≈30% over the pristine sample. Furthermore, SOECs based on the proposed cathode demonstrate excellent stability over 300 h for pure CO2 electrolysis. The addition of lithium with high basicity, low valance, and small radius, coupled with A-site deficiency, promotes the formation of oxygen vacancy and modifies the electronic structure of active sites, thus enhancing CO2 adsorption, dissociation process, and CO desorption steps as corroborated by the experimental analysis and the density functional theory calculation. It is further confirmed that Li-ion migration to the cathode surface forms carbonate and consequently provides the perovskite cathode with an impressive anti-carbon deposition capability, as well as electrolysis activity.

Bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P derived from zeolitic imidazolate framework as an efficient trifunctional electrocatalyst for water splitting and Zn-air batteries

The development of high-performance and stable trifunctional electrocatalysts is a pressing challenge for the practical application of water splitting and regenerative Zn-air batteries. Herein, bamboo-like N-doped carbon tubes encapsulated Co2P–Fe2P nanoparticles (CoFe-PN/C) was fabricated via a facile template-sacrificial approach by using CoZn-ZIF trapping Fe3+ (CoFeZn/C) as the precursor. The incorporation of Fe3+ was achieved by the one-pot synthesis approach during crystallization of ZIF, which led to the generation of the unique bamboo-like tube structure under the condition of simultaneous phosphating and carbonization. Benefiting from the large surface area, the optimized electronic structure of active sites and the unique bamboo-like nanotube, the resultant CoFe-PN/C can be used as the trifunctional electrocatalyst possessing a small overpotential at 10 mA cm−2 for the HER (178 mV) and OER (300 mV), as well as a high half-wave potential of 0.884 V for ORR (40 mV more positive than that of commercial 20 wt% Pt/C). Moreover, the self-designed CoFe-PN/C||CoFe-PN/C alkaline electrolyzer driving 50 mA cm−2 only need operating potential of 1.84 V and the maximum discharge power density of the CoFe-PN/C-assembled ZABs could achieve 152.0 mW cm−2, superior to those of Pt/RuO2 couple. This work will facilitate the development and application of trifunctional electrocatalysts based on bi-transition metallic phosphides for energy conversion and storage technology.

Modulating interfacial charge redistribution of Ni2P/CuCo2S4 p-n nano-heterojunctions for efficient electrocatalytic overall water splitting

Fabricating effective yet inexpensive catalysts is an important target in the research of water electrolysis and clean energy generation. Key challenges still remaining in this area are the rich density of surface-active sites, efficient interfacial charge transfer and improved reaction kinetics. Herein, Ni2P/CuCo2S4 p-n junctions are constructed via an in situ hydrothermal growth of Ni2P nanoparticles on CuCo2S4 nanosheets. Extensive X-ray photoelectron, optical absorption and electrochemical spectroscopy studies coupled with density functional theory calculations provide a mechanistic understanding of the electrochemical behaviour of these catalysts. The integrated Ni2P/CuCo2S4 p-n junctions, owing to the intimate interfacial interactions, offer interesting possibilities to purposively modulate the electronic structure of active sites at the interface, and thus to improve the hydrogen adsorption energetics and electrochemical reaction kinetics. As a result, the catalyst with 30 wt% Ni2P content displays high intrinsic electrocatalytic activity, requiring overpotentials of 183 and 360 mV to deliver 10 mA cm−2 for HER and 40 mA cm−2 for OER in alkaline media, respectively, far lower than those of individual Ni2P (400 and 520 mV) and CuCo2S4 (348 and 380 mV), further showing remarkable durability for 30 h. In addition, an alkaline two-electrode water electrolyzer assembled by Ni2P/CuCo2S4 nano-heterojunctions exhibits a relatively low cell potential of 1.67 V at 10 mA cm−2. These Ni2P-modified CuCo2S4 heterostructures demonstrate great potential for renewable hydrogen production technologies, including water electrolysis.

A Wide‐Temperature Adaptive Aqueous Zinc‐Air Battery‐Based on Cu–Co Dual Metal–Nitrogen‐Carbon/Nanoparticle Electrocatalysts

Zinc‐air batteries (ZABs) are promising electrochemical energy storage devices, but the inherent semi‐open configuration and catalytically dependent working principle make their performance vulnerable to temperature. Herein, a tunable multi‐site electrocatalyst is manufactured as the cathode for wide‐temperature adaptive aqueous ZABs, comprising Cu–Co dual metal–nitrogen–carbon‐coupled with metal nanoparticles (CuCo‐NC/NPs). The multi‐components synergistically optimize the electronic structure of active sites in CuCo‐NC/NPs, which endows them with low apparent activation energy (Ea) and high activity for oxygen reduction reaction. Moreover, the CuCo‐NC/NPs‐based aqueous ZABs demonstrate satisfactory stability over 540 h, and a high specific capacity of 806 mAh gzn−1 at 10 mA cm−2 at room temperature, outperforming that of Pt/C and many recent report catalysts based ZABs. Even at −30 and 60 °C, the assembled ZABs can deliver more than 88.1% and 95.5% of its room‐temperature specific capacity, as well as superior cycling stability, paving the way for practical applications of aqueous ZABs under extreme conditions.

Boosting Hydrogen Evolution in Neutral Medium by Accelerating Water Dissociation with Ru Clusters Loaded on Mo2CTx MXene

AbstractElectrocatalytic hydrogen evolution reaction (HER) in mild neutral medium is a compelling goal for environmentally sustainable energy conversion, but its development is greatly limited by slow kinetics. Platinum group noble metals exhibit ultra‐high HER activities, but their scarcity and performance instability restrict wide application. Herein, taking advantage of excellent catalyst carrier properties of 2D‐layered transition metal carbides (MXenes), highly dispersed of Ru clusters anchored on Mo2CTx MXene are demonstrated as a superior HER electrocatalyst, which is prepared by a facile in situ reduction strategy. The as‐prepared Ru/Mo2CTx catalyst exhibits a very low overpotential of 73 mV to achieve a current density of −10 mA cm−2 and Tafel slope of 57 mV dec−1 in neutral medium, surpassing performance of most previously reported MXene‐based catalysts. In addition, Ru/Mo2CTx catalyst also presents superior stability compared to commercial Pt/C. Experimental results and theoretical calculations indicate that the interaction between Ru clusters modulates the electronic structure of active sites and promotes H2O dissociation and hydrogen desorption.

Co3+-rich CoFe-PBA encapsulated in ultrathin MoS2 sheath as integrated core-shell architectures for highly efficient OER

Highly active and stable oxygen evolution reaction (OER) electrocatalyst is the key component of sustainable water splitting reaction. Controllable core-shell engineering is one of the most effective strategies for modulating the local electronic structure of active sites to enhance catalytic activity. Herein, we design a nano-cube of Co3+-rich CoFe Prussian blue analogues coated with controllable MoS2 shell heterostructures as OER electrocatalyst by simple solvothermal method, named as CoIIIFe-PBA/MoS2. Importantly, CoIIIFe-PBA/MoS2 possesses an extremely low overpotential of 306 mV at the current density of 100 mA cm−2, a small Tafel slope of 36.2 mV dec−1 and excellent stability for OER. The results of spectroscopic characterizations reveal that the Co3+ species with more 3d electron orbits origin from the charge transfer between CoFe-PBA and MoS2 core-shell interface, which promotes the electron accepting and results in the higher electrochemical activity. This research offers unique insight to design other advanced electrocatalysts with high-valent transition metal ions and core-shell structure.