High-performance Catalysts Research Articles

Leveraging Iron in the Electrolyte to Improve Oxygen Evolution Reaction Performance: Fundamentals, Strategies, and Perspectives.

Electrochemical water splitting is a pivotal technology for storing intermittent electricity from renewable sources into hydrogen fuel. However, its overall energy efficiency is impeded by the sluggish oxygen evolution reaction (OER) at the anode. In the quest to design high-performance anode catalysts for driving the OER under non-acidic conditions, iron (Fe) has emerged as a crucial element. Although the profound impact of adventitious electrolyte Fen+ species on OER catalysis had been reported forty years ago, recent interest in tailoring the electrode-electrolyte interface has spurred studies on the controlled introduction of Fe ions into the electrolyte to improve OER performance. During the catalytic process, scenarios where the rate of Fen+ deposition on a specific host material outruns that of dissolution pave the way for establishing highly efficient and dynamically stable electrochemical interfaces for long-term steady operation. This review systematically summarizes recent endeavors devoted to elucidating the behaviors of in situ Fe(aq.) incorporation, the role of incorporated Fe sites in the OER, and critical factors influencing the interplay between the electrode surface and Fe ions in the electrolyte environment. Finally, unexplored issues related to comprehensively understanding and leveraging the dynamic exchange of Fen+ at the interface for improved OER catalysis are summarized.

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. 

Exploiting Lattice Carbon-Induced Modulation Effect in Nickel towards Efficient Alkaline Hydrogen Oxidation.

Doping with non-metallic heteroatom is an effective approach to tailor the electronic structure of Ni for enhancing its alkaline hydrogen oxidation reaction (HOR) catalytic performance. However, the modulation of HOR activity of Ni by lattice carbon (LC) atoms has rarely been reported, especially to reveal the rule between the doping effect and activity caused by the content of LC atoms. Here, hydrogen is proposed as a scavenger for LC atoms in the pyrolytic reduction process to finely control the content of LC atoms in Ni. With the removal of LC atoms in Ni lattice, the electronic structure changes from Ni3C-like electronic structure to quasi-Ni structure. Furthermore, a volcanic relationship between the LC content and HOR activity of Ni is established for the first time. The Cless-Ni (LC0.44-Ni) with optimized LC content shows the best activity owing to the weakened hydrogen binding energy (HBE) and optimal hydroxyl binding energy (OHBE). This work provides an inspiration for the design of high-performance catalysts by tailoring the electronic structure of the metal via LC atoms doping.

Engineering Subnanometric Electronic Interaction between Ru and Mn in Zeolite Boosts Catalytic Oxidation of Dichloromethane.

Designing catalysts with both activity and stability remains a grand challenge for the removal of chlorinated volatile organic compounds (CVOCs) by catalytic oxidation. Herein, the Ru-Mn subnanometric species encapsulated in ZSM-5 zeolite (RuMn@Z) was synthesized. It shows that the 90% conversion of dichloromethane is as low as 320 °C, which is significantly lower than that of Ru@Z (350 °C) and the impregnation catalyst (RuMn/Z, 355 °C). Importantly, the RuMn@Z catalyst exhibits excellent high-temperature resistance (800 °C for 10 h), water resistance, long-term stability, and cyclic stability. Different from the RuMn/Z with nanoscale metal interaction, Ru and Mn species in RuMn@Z have strong electronic interaction on the subnanometric scale due to the confinement effect of zeolite. As the electronic structure regulator, the Mn species keeps the Ru species in an electron-deficient state through the Ru-O-Mn bonds, which effectively activates lattice oxygen species and molecular oxygen to participate in the reaction. Moreover, the confinement effect also makes the acid tightly coupled with the redox site, which promotes the rapid conversion of dechlorination products, formates, and other intermediate products. Therefore, this study provides valuable insights into the design of high-performance catalysts for CVOCs removal and other environmental fields.

Tunable NiSe-Ni3Se2 Heterojunction for Energy-Efficient Hydrogen Production by Coupling Urea Degradation.

Urea-assisted water splitting is a promising energy-saving hydrogen (H2) production technology. However, its practical application is hindered by the lack of high-performance bifunctional catalysts for urea oxidation reaction (UOR) and hydrogen evolution reaction (HER). Herein, a heterostructured catalyst comprising highly active NiSe and Ni3Se2, along with a conductive graphene-coated nickel foam skeleton (NiSe-Ni3Se2/GNF) is reported. The heterostructured NiSe-Ni3Se2 originates from the in situ selenization of graphene-coated nickel foam, allowing for careful regulation of the NiSe to Ni3Se2 ratio by simply adjusting the calcination temperature. Theoretical calculations of the charge transfer between NiSe and Ni3Se2 components can optimize the reaction pathways and reduce the corresponding energy barriers. Accordingly, the designed catalyst exhibits excellent UOR and HER activity and stability. Furthermore, the NiSe-Ni3Se2/GNF-based UOR-HER electrolyzer requires only 1.54V to achieve a current density of 50mA cm-2, which is lower than many recent reports and much lower than 1.83V of NiSe-Ni3Se2/GNF-based OER-HER electrolyzers. Moreover, the UOR-HER electrolyzer exhibited negligible cell voltage variation during a 28-h stability test, indicating satisfactory stability, which provides a new viable paradigm for energy-saving H2 production.

Tunable heteroassembly of 2D CoNi LDH and Ti3C2 nanosheets with enhanced electrocatalytic activity for oxygen evolution.

The sluggish kinetics of the oxygen evolution reaction (OER) is the bottleneck to developing hydrogen energy based on water electrolysis, which can be significantly improved using high performance catalysts. In this context, CoNi layered double hydroxide (LDH)/Ti3C2 heterostructures are obtained using electrostatic attraction of the positively charged LDH and negatively charged Ti3C2 nanosheets as the catalyst to optimize the OER performance. Such alternate stacking exhibits good catalytic activity with a lower overpotential and a small Tafel slope, outperforming their individual components. The results of density functional theory (DFT) simulation show that the charge transfers from Ti3C2 to CoNi LDH not only adjust the electron distribution, but also increase the electron density of the interfacial active sites, thus enhancing the electron transfer efficiency inside the heterostructures. Moreover, the cobalt and nickel ions exhibit a synergistic effect in supplying more electrons to adsorb the adjacent intermediates with active hydrogen and oxygen vacancies, to improve the adsorption capability and to reduce the reaction energy barriers. These findings provide a rewarding avenue towards the design of highly efficient electrocatalysts for OER.

Development of supported intermetallic compounds: advancing the Frontiers of heterogeneous catalysis.

Intermetallic compound (IMC) catalysts have garnered significant attention due to their unique surface and electronic properties, which can lead to enhanced catalytic performance compared to traditional monometallic catalysts. However, developing IMC materials as high-performance catalysts has been hindered by the inherent complexity of synthesizing nanoparticles with well-defined bulk and surface compositions. Achieving precise control over the composition of supported bimetallic IMC catalysts, especially those with high surface area and stability, has proven challenging. This review provides a comprehensive overview of the recent progress in developing supported IMC catalysts. We first examine the various synthetic approaches that have been explored to prepare supported IMC nanoparticles with phase-pure bulk structures and tailored surface compositions. Key factors influencing the formation kinetics and compositional control of these materials are discussed in detail. Then the strategies for manipulating the surface composition of supported IMCs are delved into. Applications of high-performance supported IMCs in important reactions such as selective hydrogenation, reforming, dehydrogenation, and deoxygenation are comprehensively reviewed, showcasing the unique advantages offered by these materials. Finally, the prevailing research challenges associated with supported IMCs are identified, including the need for a better understanding of the composition-property relationships and the development of scalable synthesis methods. The prospects for the practical implementation of these versatile catalysts in industrial processes are also highlighted, underscoring the importance of continued research in this field.

Precipitated-crosslinked multi-enzyme hybrid nanoflowers for efficient synthesis of α-ketoglutaric acid

Cascade catalysis of glutamate oxidase (GLOX) and catalase (CAT) to perform one-pot synthetic route for α-ketoglutarate (α-KG) production offers several advantages including simplicity of operation and the generation of few reaction by-products. Nevertheless, the instability of free GLOX and CAT, the high production cost and the difficulty of recycling severely limits its industrial utilisation. Here, catalase-inorganic hybrid nanoflowers were first prepared, and cross-linked with GLOX precipitates by a macromolecular cross-linking agent dextran polyaldehyde to form a novel dual enzyme precipitation-cross-linking hybrid nanoflower (GLOX@CAT-HNFs). The resultant GLOX@CAT-HNFs exhibited higher catalytic activity than conventional combined cross-linked enzyme aggregates (combi-CLEAs) and hybrid nanoflowers (GLOX&CAT-HNFs). The GLOX@CAT-HNFs exhibited 92 % activity recovery whereas combi-CLEAs and GLOX&CAT-HNFs was 87 % and 72 %, respectively. Meanwhile, the GLOX@CAT-HNFs showed better thermal stability, pH and storage stability than free enzymes. After incubation at 60 °C for 100 min, GLOX@CAT-HNFs maintained 70 % of its initial activity while free enzyme was only 18.52 %. Furthermore, after 7 cycles of use, GLOX@CAT-HNFs maintained 68.79 % of its initial activity, indicating excellent reusability. Benefiting from the excellent stability and reusability of GLOX@CAT-HNFs, a nearly 100 % (99.64 %) conversion of L-glutamate to α-KG was achieved, over 1.79 times higher than that of the free GLOX system (55.53 %). This work provides a feasibility for constructing a high-performance cascade catalyst of multiple enzymes.

Reducing noble metal dependence: oxygen evolution reaction with a Ru-minimized Bi2Ru2O7@MOF-801 composite.

Developing efficient and noble metal-minimized electrocatalysts for the oxygen evolution reactions (OER) is critical for energy conversion reactions. Here we present Ru-minimized Bi2Ru2O7@MOF-801 that synergistically combines the high catalytic activity of the bimetallic oxide with the unique structural and hydrophilic properties of the Zr-MOF. The composite achieves superior OER performance with a low overpotential of 307 mV at 50 mA cm-2 and a Tafel slope of 99.8 mV dec-1 surpassing those of pure Bi2Ru2O7 and MOF-801. Comparative testing with cutting-edge catalysts shows that using less Ru and incorporating a MOF work well together, providing a promising way to make high-performance OER catalysts that are also cost-effective by integrating the MOF for energy applications.

Encapsulated Fe3C boosted electrocatalytic performance for oxygen reduction reaction of N-doped carbon nanotube

The shortcomings of precious metal based catalysts have limited the development of novel energies. So, developing low-cost and high performance transition metal based catalysts is one of the most feasible way to substitute the precious metal based catalysts. In all of the developed catalysts for oxygen reduction reactions (ORR), the iron-based nitrogen doped carbon nanotube (N-CNT) show great promise. In this paper, N-CNT with Fe3C encapsulated based catalysts (Fe3C@N-CNT) were synthesized. The encapsulation structure of Fe3C@N-CNT was confirmed by HAADF-STEM, XANES, XPS, XRD, SEM and other methods. XANES tests show that the doped nitrogen of Fe3C changed the length of Fe-C bond and furtherly influenced the electron transfer between encapsulated Fe3C and outer layer N-CNT. Electrochemical tests showed that the half-wave potential and onset potential ORR of 750 °C calcinated Fe3C@N-CNT were 90 mV higher than that of 20 wt.% Pt/C. The additional electric field between Fe3C and N-CNT modulated the C-N bond of surface N-CNT and enhanced the catalytic performance for ORR. This paper reveal that constructing encapsulated additional electron providing center is an effective way to design high performance catalysts.

Synergistic Improvement of pH-Universal Hydrogen Evolution through B, N Dual-Doped Mo2C

The quest for a cost-effective, high-performance catalyst for hydrogen production from electrolyzed water across a broad pH range holds immense importance. B, N co-doped Mo2C was first synthesized via microwave...

Cluster-like Mo2N anchored on reduced graphene oxide as an efficient and high-performance catalyst for deep-degree oxidative desulfurization

The cluster-like Mo2N catalyst, uniformly dispersed on the graphene surface, was successfully prepared. The resulting Mo2N/rGO-A catalyst exhibited plentiful accessible surface active sites, exhibiting efficient and high-performance for ODS.

Versatile electrospun cobalt-doped carbon films for rapid antibiotic degradation.

This study presents a novel approach to water contamination remediation by developing cobalt-doped carbon nanofiber films using electrospun ZIF-67 precursors, aiming to degrade tetracycline hydrochloride (TCH) and other antibiotics. This method uniquely combines the advantages of metal-organic frameworks (MOFs) and electrospinning to enhance catalytic performance, demonstrating significant innovation in environmental catalysis. The research systematically evaluated the impact of various factors on the catalytic activity of carbonized PAN@ZIF-67 films (CPZF), including carbonization temperature, ZIF-67 content, and PMS dosage. Notably, the CPZF catalyst with 11% ZIF-67 content (named as CPZF-11%) achieved an impressive 99.7% degradation of TCH within just 10 min under visible light and PMS activation, highlighting its superior catalytic efficiency. The study revealed that CPZF-11% exhibited excellent stability and recyclability, maintaining near 100% degradation rates even after six cycles. This catalytic performance is attributed to the synergistic effect of photogenerated electrons and PMS activation, leading to the formation of reactive oxygen species (ROS) such as sulfate radicals and singlet oxygen. The research further elucidated the degradation pathways and intermediate products through quenching experiments and electron paramagnetic resonance (EPR) analysis. The findings demonstrate the broad applicability of CPZF/Vis/PMS in various water matrices, including tap water and wastewater, underscoring its potential for real-world applications in wastewater treatment. This innovative integration of MOFs and electrospinning offers a promising strategy for developing efficient, recyclable, and high-performance catalysts for environmental remediation.

Janus Cobalt Sites on Carbon Nitride for Efficient Photocatalytic Overall Water Splitting

Regulating the dual active sites is crucial for enhancing the carrier-directed migration efficiency and shortening mass transfer distance of intermediates, particularly in photocatalytic overall water splitting. In this paper, we adopt in situ hydrothermal coupled gas phase chemical reduction methods to synthesize janus cobalt cocatalysts on g-C3N4. Experimental measurement and density functional theory calculations show that the janus cobalt cocatalysts fine-tunes the local electronic structure of g-C3N4, which can greatly reduce energy barriers and shorten mass transfer distance of intermediates for reactions. And while the built-in electric field of CoP and CoO also further efficiently facilitates rapid directional separation of interface carriers of the cocatalysts. This study elucidates atom-level mechanisms underlying overall water splitting and offers valuable insights for rational design of high-performance catalysts for overall water splitting. As a result, the CoP/CoO@g-C3N4 samples exhibit a remarkable enhancement in overall water splitting activity (133.2 μmol g−1 h−1 H2 and 67.2 μmol g−1 h−1 O2), surpassing that of the CoP@g-C3N4 and CoO@g-C3N4 samples by 1.4 and 3.8 times, respectively.

Hydrogen-intercalation PdZn bimetallene for urea electro-synthesis from nitrate and carbon dioxide

We have reported the incorporation of hydrogen into PdZn bimetallene, showing excellent performance for electrosynthesis of urea due to the optimized adsorption energy of intermediates.

Electronic Promoter Breaks the Linear Scaling Relationship: Ultra‐Rapid High‐Temperature Synthesis of Heterostructured CoS/SnO2@C as a Bifunctional Oxygen Catalyst for Li‐O2 Batteries

AbstractLi‐O2 batteries urgently needs high discharge capacity and stable cycling performance, requiring effective and reliable bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Hovenia acerba Lindl‐like heterostructure composed of cobalt sulfide and tin dioxide supported on carbon substrate (CoS/SnO2@C) is prepared via CO2 laser irradiation technology. The half‐wave potential of CoS/SnO2@C for the ORR is 0.88 V, while the overpotential of the OER at 10 mA cm−2 is as low as 270 mV. The Li‐O2 batteries employing the bifunctional CoS/SnO2@C catalyst displays a high discharge specific capacity of 3332.25 mAh g−1 and long cycling life of 226 cycles. Additionally, theory calculations demonstrate that the construction of heterostructure decreases energy barrier of the rate‐determining step (RDS) for both ORR and OER. Notably, SnO2 behaves as the electronic promoter to optimize the electronic structure of heterostructure interface and triggers charge redistribution of CoS, which weakens the adsorption strength of the *O‐intermediates and allows to break the linear scaling relationship, thus further enhancing the catalytic performance of CoS/SnO2@C. This research furnishes directions for the design of heterogeneous catalysts, highlighting its great potential for application in rechargeable Li‐O2 batteries.

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.

Electronic Structure Modulation Induced by the Synergy of Cobalt Low-Nuclearity Clusters and Mononuclear Sites for Efficient Oxygen Electrocatalysis.

The development of high-performance bifunctional single-atom catalysts for use in applications, such as zinc-air batteries, is greatly impeded by mild oxygen reduction and evolution reactions (ORR and OER). Herein, we report a bifunctional oxygen electrocatalyst designed to overcome these limitations. The catalyst consists of well-dispersed low-nuclearity Co clusters and adjacent Co single atoms over a nitrogen-doped carbon matrix (CoSA+C/NC). The precisely tailored asymmetric electronic structures are achieved with strong electronic interactions between these Co species. The Co clusters optimize the adsorption/desorption strength of oxygenated intermediates on single-atomic Co sites to endow exceptional activity under alkaline conditions with a half-wave potential (E1/2) of 0.91 V and an overpotential (η) of 340 mV at 10 mA cm-2. In addition, a zinc-air battery assembled with CoSA+C/NC achieves a high power density of 284.1 mW cm-2 and a long operational lifespan of 400 h, superior to those of the benchmark Pt/C + RuO2. Experimental findings and theoretical analysis reveal that the enhanced bifunctional activity stems from the synergistic interactions between Co clusters and single-atomic Co sites. Consequently, the overbinding of *OH is suppressed with accelerated *OH removal. This work establishes the design principle of advanced electrocatalysts with multiphase metal species bearing strong electronic interactions.

Innovative spherical Fe-Mn layered double hydroxides (LDH) for the degradation of sulfisoxazole through activated periodate: Efficacy and mechanistic insights.

Advanced oxidation technology based on peroxides is widely regarded as an efficient method for treating emerging contaminants. However, the precise mechanism by which layered double hydroxides (LDHs) enhance oxidant activation requires further investigation. In this study, a spherical Fe-Mn LDH (S-FML) with improved crystallinity using a simple hydrothermal method. Compared to granular Fe-Mn LDH (G-FML), S-FML demonstrated superior periodate (PI) activation efficiency and outstanding stability. Intensive mechanistic studies have shown that the synergistic action of Fe2⁺ and Mn2⁺ in S-FML plays a key role in the degradation reaction. Three primary pathways for SIZ degradation and a reduction in solution toxicity post-reaction were identified through analysis of degradation intermediates and density functional theory (DFT) calculations. This research offers valuable theoretical insights and a scientific foundation for designing high-performance heterogeneous catalysts and elucidating the efficient activation mechanisms of PI for emerging pollutant treatment.

FeCu-N6-C Diatomic Sites Catalyst for the Boosted Oxygen Reduction Reactions in Zinc-Air Batteries.

Due to the high catalytic activity and stability for oxygen reduction reaction, N-coordinated Fe-Cu dual-metal doped carbon material (FeCu-N-C) is considered to be one of the promising electrode materials for metal-air battery and fuel cells. Herein, FeCu-N-C dual-metal catalysts was synthesized by an adsorption-calcination strategy. The prepared FeCu-N-C exhibited high activity and stability both in alkaline and acidic media. In alkaline/acid medium, the half-wave potential reaches to 0.90/0.80 V, which is better than Fe-N-C catalyst. The power density for FeCu-N-C in zinc-air battery reaches to 220 mW cm-2 and shows high electrochemical stability for more than 600 hours in charge/discharge cycles, much higher than 130 hours for Pt/C (40 %) and 100 hours for Fe-N-C. Density-functional theory calculations showed that the FeCu-N-C dual-metal catalysts got lower overpotential of 0.50 V than Fe-N-C (0.53 V), which improved the ORR activity. The results are helpful for the deep understanding of high-performance diatomic catalysts.