High-performance Electrocatalysts Research Articles

High performance energy-saving electrocatalysts for hydrogen evolution reaction: A minireview on the influence of structure and support

Abstract Generating hydrogen from water electrolysis is a promising clean energy strategy that may help alleviate energy crisis, which stimulates tremendous research interests in searching high performance catalysts with low energy consumption. In this article, we review recent progresses on the development of high performance electrocatalysts for hydrogen evolution reaction (HER) from the energy consumption perspective with the emphasis on the structure impact and support. In particular, the structural influence on the energy conversion efficiency and stability of HER electrocatalysts is discussed, and the role of support carriers in forming energy-saving catalytic systems with minimized non-HER energy loss, which are vital for practical processes, is highlighted. Moreover, a global design strategy incorporating both catalyst and support in the same integrated framework is advocated. This paper provides new insights into the structure-property relationship and the support effect in developing highly efficient and durable electrocatalysts for HER. 

Microbial-induced Synthesis of nano NiFe LDH for High-efficiency Oxygen Evolution.

NiFe layered double hydroxide (LDH) currently are the most efficient catalysts for the oxygen evolution reaction (OER) in alkaline environments. However, the development of high-performance low cost OER electrocatalysts using straightforward strategies remains a significant challenge. In this study, we describe an innovative microbial mineralization-based method for in situ-induced preparation of NiFe LDH nanosheets loaded on nickel foam and demonstrate that this material serves as an efficient oxygen evolution electrocatalyst. In the microbial mineralization process, bacteria adhere to electrode materials and promote the surface nucleation of nanomaterials when metal ions are present. Specifically, our findings indicate that biomineralization accelerates the formation and regulation of NiFe LDH. The new electrocatalyst displays excellent OER performance, with a small overpotential of 220 mV at 10 mA cm-2 and a Tafel slope down to 38.6 mV dec-1 in alkaline solution. The remarkable OER performance of the microbial mineralization-derived electrocatalyst is attributed to the synergistic effect of NiFe LDH and a bacterial-specific surface area that contains multiple active sites. This study has uncovered a new approach for the assembly of NiFe LDH that relies on biomineralization to bring about morphological and structural modification of LDH nanosheets.

Utilizing waste lithium-ion batteries for the production of graphite-carbon nanotube composites as oxygen electrocatalysts in zinc–air batteries

This study presents a new method to transform Li-ion battery recycling residue into a high-performance oxygen electrocatalyst for zinc–air batteries.

High-performance bifunctional electrocatalysts for zinc-air batteries using coaxial electrospun hollow N-doped carbon nanofibers decorated with NiCo and CoMn nanocrystals

High-performance bifunctional electrocatalysts for zinc-air batteries using coaxial electrospun hollow N-doped carbon nanofibers decorated with NiCo and CoMn nanocrystals

Construction of core-shell NiFe LDH/Co(OH)F amorphous/crystalline heterostructure for synergistically enhanced electrocatalytic water oxidation

The development of high performance non-precious transition metal electrocatalysts for the oxygen evolution reaction (OER) is essential for the practical application of electrocatalytic water splitting. A promising strategy to prepare highly efficient and stable electrocatalysts for the OER can be achieved by constructing heterointerfaces between the amorphous and crystalline phases. Herein, a novel three-dimensional (3D) core-shell structured NiFe-LDH/Co(OH)F electrocatalyst on nickel foam (NF) with an amorphous/crystalline interface was achieved by growing 2D amorphous NiFe LDH nanosheets onto 1D crystalline Co(OH)F nanorod arrays using a simple two-step hydrothermal method. The resulting NiFe LDH/Co(OH)F/NF electrode exhibits outstanding electrochemical OER performance with an overpotential of 202 and 260mV at the current density of 10 and 100mAcm-2, a Tafel slope of 44.06mV dec-1, and an ultra-high stability over 100h at 300mAcm-2 without obvious degradation in 1M KOH. This research affords a new way to construct high-performance 3D hierarchical non-noble metal electrocatalysts for OER.

Iridium-based electrocatalysts for the hydrogen oxidation reaction toward alkaline exchange membrane fuel cells

This review highlights recent advances in Ir-based electrocatalysts based on different design strategies. This review will guide future research in the development of high-performance Ir-based HOR electrocatalysts for AEMFCs.

Developing porous electrocatalysts to minimize overpotential for the oxygen evolution reaction.

The development of electrocatalysts for the oxygen evolution reaction (OER) is one of the most critical issues for improving the efficiency of electrochemical water-splitting, which can produce green hydrogen energy without CO2 emissions. This review outlines the advances in the precise design of inorganic- and organic-based porous electrocatalysts, which are designed by various strategies, to catalyze the OER in the electrolytic cycle for efficient water-splitting. For developing high-performance electrocatalysts with low overpotentials, it is important to design a chemical composition that optimizes binding energy for an intermediate in the OER and allows the easy access of reactants to active sites depending on the porosity of electrocatalysts. Porous structures give us the positive opportunity to increase the accessible surface of active sites and effective diffusion of targeting molecules, which is potentially one of the guidelines for developing active electrocatalysts. Further modification of the frameworks is also powerful for tailoring the function of pore surfaces and the environment of inner spaces. Designable organic molecules can also be embedded inside inorganic- and organic-based frameworks. According to chemical composition (inorganic and organic), nanostructure (crystalline and amorphous) and additional modification (metal doping and organic design) of porous electrocatalysts, the current status of resultant OER performance is surveyed with some problems that should be solved for improving the OER activity. The remarkable progress in OER electrocatalysts is also introduced for demonstrating the bifunctional hydrogen evolution reaction (HER) and for utilizing seawater.

Stabilizing *CO intermediate on nitrogen-doped carbon-coated CuxOy derived from metal-organic framework for enhanced electrochemical CO2-to-ethylene

The electrochemical CO2 reduction reaction (CO2RR) provides a means for producing ethylene, but its selectivity and stability still need further improvement. Therefore, the development of high-performance electrocatalysts is particularly important....

Three-dimensional nitrogen-doped graphene quantum dot/Ag leaf/Cu2O-Cu trunk/nickel foam nanocomposites as ultra-high-efficiency cathode electrocatalysts for hydrogen evolution reaction applications

In this study, we developed a three-dimensional (3D) nitrogen-doped graphene quantum dot (NGQD)/Ag leaf/Cu₂O-Cu trunk/nickel foam (NF) structure as a high-performance electrocatalyst for hydrogen evolution reaction (HER) applications. This novel structure exhibited a high surface area, abundant electrochemically active sites, and efficient electronic transmission networks. In alkaline solution, the proposed structure demonstrated an overpotential of 112 mV at a current density of 10 mA/cm2, along with a low Tafel slope of 28 mV dec−1, indicating excellent HER activity. Furthermore, the structure exhibited stability over 100 h during durability testing. Overall, this innovative structure experimentally confirms that Cu-based materials can serve as efficient electrocatalysts for HER applications.

Electrocatalytic properties of ultrathin FeSe2/Ni0·85Se heterostructure hollow nanobelts for oxygen evolution in alkaline water and simulated seawater

Research into cost-effective electrocatalysts for alkaline water and simulated seawater oxidation is paramount for advancing the conversion and storage of renewable energy. In this study, a FeSe2/Ni0·85Se catalyst with the hollow and ultrathin nanobelts structure is synthesized. The distinctive structure characteristics of FeSe2/Ni0·85Se heterojunction nanobelts confer exceptional oxygen evolution reaction (OER) properties in diverse electrolytes, including alkaline 1 M KOH and simulated seawater (1 M KOH + 0.5 M NaCl) solutions. The FeSe2/Ni0·85Se catalyst presents the low overpotentials of 259 and 267 mV at a current density of 10 mA cm−2, along with the Tafel slopes of 33.7 and 65.5 mV dec−1 in two solutions, respectively. Additionally, the FeSe2/Ni0·85Se catalyst also demonstrates good stability. This exploration introduces a promising strategy for the development of high-performance electrocatalysts in the realm of green energy, marking the significant progress towards sustainable energy solutions.

High-performance electrocatalyst of activated carbon-decorated molybdenum trioxide nanocomposites for effective production of H2 and H2O2

High-performance electrocatalyst of activated carbon-decorated molybdenum trioxide nanocomposites for effective production of H2 and H2O2

N-heterocyclic carbene coordinated single atom catalysts on C2N for enhanced nitrogen reduction

Single-atom catalysts (SACs) with N-heterocyclic carbene (NHC) coordination provide an effective strategy for enhancing nitrogen reduction reaction (NRR) performance by modulating the electronic properties of the metal active sites. In this work, we designed a novel NHC-coordinated SAC by embedding transition metals (TM) into a two-dimensional C2N-based nanomaterial (TM@C2N-NCM) and evaluated the NRR catalytic performance using a combination of density functional theory and machine learning. A multi-step screening identified eight high-performance catalysts (TM = Nb, Fe, Mn, W, V, Ta, Zr, Ti), with Nb@C2N-NCM showing the best performance (limiting potential = -0.29 V). All catalysts demonstrated lower limiting potential values compared to their TM@graphene-NCM counterparts, revealing the effectiveness of the C2N substrate in enhancing catalytic activity. Machine learning analysis achieved high predictive accuracy (coefficient of determination = 0.91; mean absolute error = 0.19) and identified final step protonation (S6), Mendeleev number (Nm), and d-electron count (Nd) as key factors influencing catalytic performance. This study offers valuable insights into the rational design of NHC-coordinated SACs and highlights the potential of C2N-based nanomaterials for advancing high-performance NRR electrocatalysts.

Effective Nitrate Electroconversion to Ammonia Using an Entangled Co3O4/Graphene Nanoribbon Catalyst.

There has been huge interest among chemical scientists in the electrochemical reduction of nitrate (NO3-) to ammonia (NH4+) due to the useful application of NH4+ in nitrogen fertilizers and fuel. To conduct such a complex reduction reaction, which involves eight electrons and eight protons, one needs to develop high-performance (and stable) electrocatalysts that favor the formation of reaction intermediates that are selective toward ammonia production. In the present study, we developed and applied Co3O4/graphene nanoribbon (GNR) electrocatalysts with excellent properties for the effective reduction of NO3- to NH4+, where NH4+ yield rate of 42.11 mg h-1 mgcat-1, FE of 98.7%, NO3- conversion efficiency of 14.71%, and NH4+ selectivity of 100% were obtained, with the application of only 37.5 μg cm-2 of the catalysts (for the best catalyst ─Co3O4(Cowt %55)GNR, only 20.6 μg cm-2 of Co was applied), confirmed by loadings ranging from 19-150 μg cm-2. The highly satisfactory results obtained from the application of the proposed catalysts were favored by high average values of electrochemically active surface area (ECSA) and low Rct values, along with the presence of several planes in Co3O4 entangled with GNR and the occurrence of a kind of "(Co3(Co(CN)6)2(H2O)12)1.333 complex" structure on the catalyst surface, in addition to the effective migration of NO3- from the cell cathodic branch to the anodic branch, which was confirmed by the experiment conducted using a H-cell separated by a Nafion 117 membrane. The in situ FTIR and Raman spectroscopy results helped identify the adsorbed intermediates, namely, NO3-, NO2-, NO, and NH2OH, and the final product NH4+, which are compatible with the proposed NO3- electroreduction mechanism. The Density Functional Theory (DFT) calculations helped confirm that the Co3O4(Cowt %55)GNR catalyst exhibited a better performance in terms of nitrate electroreduction in comparison with Co3O4(Cowt %75), considering the intermediates identified by the in situ FTIR and Raman spectroscopy results and the rate-determining step (RDS) observed for the transition of *NO to *NHO (0.43 eV).

Host-Guest Structure Enabling Electrocatalytic Hydrogen Evolution Performance by POM@TM-BDC Composites.

Developing economical, efficient, and earth-rich electrocatalysts for hydrogen evolution reaction (HER) is quite challenging and ideal. We propose that [P2W18O62]6- as the guest, due to its excellent reversible 18 electron-transfer capacity and redox properties, and then TM-BDC (TM = Ni, Co, Fe, BDC = 1,4-benzene-dicarboxylate) as the host make [P2W18O62]6- packaged and not escape due to its porous structure. Benefiting from strong redox-competent interactions between [P2W18O62]6- and porous structures of TM-BDC and full exposure of abundant active sites, three {P2W18}@TM-BDC composites exhibited excellent HER activity, with {P2W18}@Ni-BDC requiring 198 mV (overpotentials) and 104 mV/dec (Tafel slope) for HER. More importantly, three {P2W18}@TM-BDC composites show excellent stability, with the voltage remaining nearly constant for 24 h. Meanwhile, the linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) curves of three {P2W18}@TM-BDC overlap well with the initial curve after the stability test. Our work offers a promising strategy for synthesizing high-performance electrocatalysts and broadens the scope of nonprecious metal composite material preparation.

Unraveling the Synergistic Role of Sm3+ Doped NiFe-LDH as High-Performance Electrocatalysts for Improved Anion Exchange Membrane and Water Splitting Applications.

Effective first-row transition metal-based electrocatalysts are crucial for large-scale hydrogen energy generation and anion exchange membrane (AEM) devices in water splitting. The present work describes that SmNi0.02Fe-LDH nanosheets on nickel foam are used as a bifunctional electrocatalyst for water splitting and AEM water electrolyzer study. Tuning the Ni-to-Fe ratios in NiFe-LDH and doping with Sm ions improves the electrical structure and intrinsic activity. SmNi0.02Fe-LDH has higher oxygen evolution reaction (OER), HER, and TWS activity, achieving 10 mAcm⁻2 current density at lower overpotentials (230 mV, 95 mV, and 1.62 V, respectively). In AEMWE cells, SmNi0.02Fe-LDH as a cathode and anode pair exhibits outstanding activity (0.9 Acm⁻2 at 2 V) and stability over 120 h. Density Functional Theory (DFT) investigations reveal that the Sm doping in NiFe-LDH surface enhances its bifunctional activity toward OER and HER. These findings emphasize the potential of non-noble composites for long-term water electrolysis in total water splitting and AEMWE applications.

Cascade Reaction Enables Heterointerfaces-Enriched Nanoarrays for Ampere-Level Hydrogen Production.

Designing high-performance electrocatalysts with superior catalytic activity and stability is essential for large-scale hydrogen production via water electrolysis. Heterostructure nanoarrays are promising candidates, though achieving both high activity and stability simultaneously, especially under high current densities, remains challenging. To this end, we have developed a cascade reaction process that constructs a series of heterostructure nanoarrays with rich heterointerfaces. This process involves treating nickel foam (NF) with molten KSCN and transition metal salts. Initially, NF reacts with KSCN to form Ni9S8 nanoarrays and S2- ions, which are subsequently captured by transition metal ions to form sulfides that are directly integrated onto the nanoarrays, resulting in abundant heterointerfaces. Both experimental and theoretical results indicate that these rich heterointerfaces significantly enhance the interfacial interaction between Ni9S8 and RuS2 within the nanoarrays (termed RH-Ni9S8/RuS2), markedly improving both the intrinsic activity and stability for the hydrogen evolution reaction (HER). Impressively, the RH-Ni9S8/RuS2 demonstrates exceptional HER performance, achieving a low overpotential of just 180 mV at 1000 mA cm-2 and maintaining stability for up to 500 h under such high-current-density conditions. This innovative approach paves the way for the interfacial design and synthesis of high-performance catalysts for ampere-level hydrogen production.

Impact of the Metal-Organic Frameworks Polymorphism on the Electrocatalytic Properties of CeO2 toward Oxygen Evolution.

Hydrogen (H2) is a viable alternative as a sustainable energy source, however, new highly efficient electrocatalysts for water splitting are still a research challenge. In this context, metal-organic frameworks (MOFs)-derived nanomaterials are prominent high-performance electrocatalysts for hydrogen production, especially in the oxygen evolution reaction (OER). Here, a new synthesis of two cerium oxide (CeO2) electrocatalysts using Ce-succinates MOFs as templates is proposed. The cerium succinates polymorphs ([Ce2(Succ)3(H2O)2], Succ = succinate ligand) were obtained via hydrothermal reaction and room temperature crystallization, adopting monoclinic (C/2c) and triclinic (P1̅) crystalline structures, respectively, confirmed by X-ray diffraction (XRD). MOFs-Ce were also characterized by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). CeO2 electrocatalysts were obtained via MOFs-Ce calcination at 350 °C in air, and characterized by XRD with Rietveld refinement, HRTEM, SEM, FT-IR, and Raman spectroscopy, UV-vis spectroscopy, X-ray photoelectron spectroscopy. Electrocatalytic performances were investigated in KOH 1.0 M solution, and overpotentials were η = 326 mV (for CeO2 (H) from monoclinic MOF-Ce) and η = 319 mV (for CeO2 (RT) from the triclinic MOF-Ce) for a current density of 10 mAcm-2. The Tafel slope values show the adsorption of intermediate oxygenated species as the rate-determining step. The high values of double-layer capacitance, the presence of oxygen vacancies, and low charge transfer resistance agree with the high performance in OER. Additionally, the materials were stable for up to 24 h, according to chronopotentiometry results.

Core-Shell Quantum Wires-Supported Single-Atom Fe Electrocatalysts for Efficient Overall Water Splitting.

It is of great significance for the development of hydrogen energy technology by exploring the new-type and high-efficiency electrocatalysts (such as single atom catalysts (SACs)) for water splitting. In this paper, by combining interface engineering and doping engineering, a unique single atom iron (Fe)-doped carbon-coated nickel sulfide (Ni3S2) quantum wires (Ni3S2@Fe-SACs) is prepared as a high-performance bi-functional electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Theoretical calculation and experimental results show that the addition of atomic Fe species can effectively adjust the electronic structure of sulfide, the interfacial electron transfer modulates the d-band center position, optimizing the transient state of the catalytic process and adsorption energy of hydrogen/oxygen intermediates, and greatly accelerates the kinetics of HER and OER. The results show that the Ni3S2@Fe-SACs core-shell quantum wires array exhibit overpotentials of 46 and 219mV for HER and OER at 10mA cm-2 in 1m KOH, respectively. In addition, the two-electrode electrolyzer assembled by the Ni3S2@Fe-SACs requires a voltage as low as 1.465V to achieve alkaline overall water splitting of 10mA cm-2. This work holds great promise for the development of highly active and highly stable electrocatalysts for future hydrogen energy conversion applications.

3D-Printed Hierarchical Nanostructured N-Co2NiO4 NF Electrode for Efficient Concurrent Electrocatalytic Production of Hydrogen and Formate.

Replacing the oxygen evolution reaction with the alternative glycerol electro-oxidation reaction (GER) provides a promising strategy to enhance the efficiency of hydrogen production via water electrolysis while co-generating high-value chemicals. However, obtaining low-cost and efficient GER electrocatalysts remains a big challenge. Herein, a self-supported N-doped Co2NiO4 nanoflakes (N-Co2NiO4 NF) is proposed for efficient electrocatalytic oxidation of glycerol to formate. The synergistic effect induced by the interaction of the layered Co2NiO4 nanostructures on the 3D-printed Nickel-Yttria-stabilized zirconia (Ni-YSZ) substrate and the amorphous nitrogen-doping promotes the anodic GER. The N-Co2NiO4 NF exhibits low potentials of 1.07 and 1.18V (vs. RHE) for GER to drive 10 and 50mAcm-2, respectively. The constituted two-electrode electrolyzer (N-Co2NiO4 NF//NiS-Co-NiP) displays excellent activity that only requires ultralow cell voltages of 1.24 and 1.55V to afford 10 and 200mAcm-2, respectively, with a high FE (97%) for formate production and an excellent durability (120h). This study provides a versatile approach for manufacturing high-performance Ni-based electrocatalyst for GER, paving the way for the energy-saving and environmentally-friendly co-production of value-added chemicals and hydrogen.

Hydrogen evolution performance of single atom catalyst supported on holey graphdiyne

Abstract Electrocatalytic hydrogen production is an effective method to solve environmental issues and energy crisis. However, cheap and high performance electrocatalysts are still very scarce. In this work, the hydrogen evolution reaction performance of holey graphdiyne supported transition metals single-atom catalysts (TM-SAC-HGY) were investigated by first-principles study. It is found that TM atoms are stably anchored on monolayer HGY by forming TM-C bonds. Meanwhile, TM atoms transfer electrons to both HGY and H atom. More importantly, the H adsorption free energy (ΔG H) of Cu-SAC-HGY is 0.028 eV, which is very close to 0 eV. Therefore, Cu-SAC-HGY has excellent HER activity. By analyzing the results of partial density of states, it can be concluded that the orbital hybridization strength of TM and H plays a decisive role in affecting HER activity. This work could contribute to the development of more efficient HER electrocatalysts.