Bifunctional Catalytic Performance Research Articles

Mn-N5 structure between poly-porphyrin manganese and 3D N-doped graphene to enhance bifunctional oxygen catalytic performance

Mn-N5 structure between poly-porphyrin manganese and 3D N-doped graphene to enhance bifunctional oxygen catalytic performance

MXene-supported 2D bimetallic chalcogenide electrocatalyst: Enhanced electrochemical seawater splitting

Hydrogen energy holds immense potential for revolutionizing modern energy technologies. Seawater electrolysis is a promising strategy for hydrogen production; however, the lack of effective electrodes limits its widespread application. Therefore, developing high-performance, cost-effective catalysts for water splitting is essential for sustainable energy conversion. In this context, we report a novel hybrid bimetallic selenide (CoMoSe2) and MXene (Ti3C2Tx) electrocatalyst, which exhibits remarkable catalytic performance for seawater electrolysis. The CoMoSe2@Ti3C2Tx electrocatalyst demonstrates outstanding catalytic capabilities, achieving overpotentials of 82 mV for hydrogen evolution reaction (HER) and 329 mV for oxygen evolution reaction (OER) at a current density of 10 mA cm⁻2 in alkaline conditions. The Tafel slope values are 124 mV dec⁻1 for hydrogen evolution and 69 mV dec⁻1 for oxygen evolution, outperforming their individual components. The enhanced bifunctional catalytic performance of the hybrid catalyst is attributed to the synergistic effect of Mo atoms within the CoSe2 crystal structure, which modifies the electronic structure and lowers the chemisorption energies of hydrogen and oxygen intermediates. The abundance of oxygen vacancies provides more reactive active sites and improves electrical conductivity. Additionally, the CoMoSe2@Ti3C2Tx composite has demonstrated remarkable bifunctional electrocatalytic performance for seawater splitting, achieving 10 mA cm⁻2 at overpotentials of 161 mV for HER and 354 mV for OER in alkaline seawater. The Volmer-Heyrovsky mechanism drives the remarkable long-term stability of the catalyst. This novel approach contributes to sustainable energy solutions by providing a fresh avenue for the development of effective catalysts to produce hydrogen from seawater.

Coupling Solid and Soluble FePc Catalysts for Non-Aqueous Li-O2 Battery Applications

The development of a bifunctional catalyst for reversible oxygen reduction reactions (ORRs) and oxygen evolution reactions (OERs) is an important challenge to promote the performance of lithium-oxygen (Li-O2) batteries. Iron phthalocyanine (FePc) complex has been considered a promising candidate for a bifunctional O2 catalyst in Li-O2 batteries due to its high catalytic activities and easy preparation. Herein, a dual mediator scheme is proposed to achieve an efficient and durable O2 electrocatalyst by coupling well-design solid and electrolyte-soluble FePc-based redox mediators (RMs). Two modes of pyridine-functional carbon support in solid/soluble FePc-based RMs including carbon multi-walled carbon nanotube (Py-MWCNT) and graphene (Py-GR) are investigated to evaluate the influences of different dual RMs on their catalytic activity and kinetics. Among the as-prepared samples, the dual solid FePc-Py-MWCNT/soluble FePc-based RM reveals the best bifunctional catalytic performance, which can be attributed to the highly efficient solid/liquid interface between Li2O2 and solution phase FePc.

Optimizing Activity and Stability in AgCl‐CuO Electrocatalysts: Insights from Different Morphologies for Enhanced ORR Performance

AbstractHighly enduring and methanol‐tolerant electrocatalysts are pertinent to revolutionizing direct methanol fuel cell (DMFC) technologies. Transition‐metal‐based electrocatalysts are anticipated to rank among the remarkable electrocatalysts for boosting the sluggish oxygen reduction reaction (ORR) kinetics. In this study, we report a facile approach to optimize the activity and stability of the AgCl‐CuO systems. The tailored nanoparticle–nanorod (NP–NR) and nanoleaf (NL) like morphologies deliver remarkable bifunctional catalytic performance for oxygen reduction and hydrogen evolution reactions, sustained activity, and comparatively better stability for ORR. A meager shift of only 0.014 and 0.024 V in the half‐wave potential is observed in the NP‐NR and NL structures, respectively, for the ORR even after 2500 cycles. Furthermore, both the AgCl‐CuO composite exhibit an excellent tolerance to methanol.

Bifunctional Catalytic Performance of Zn/ZSM-5 in the Aromatization of LPG and the Conversion of Pyrolytic Gases from Recycled Polypropylene

Zn-modified ZSM-5 zeolites with different zinc contents were successfully prepared by the impregnation method and compared with unmodified ZSM-5. Their potential for LPG (liquefied petroleum gas) aromatization and the conversion of pyrolysis gases obtained from recycled polypropylene was subsequently evaluated. In this process, various characterization tests were performed on the prepared catalysts, including SEM-EDS (scanning electron microscopy with energy-dispersive spectroscopy), TPD-NH₃ (temperature-programmed desorption of ammonia), and FTIR (Fourier-transform infrared spectroscopy). Under optimized conditions, the best results were obtained with 2% Zn/ZSM-5, which generated a higher production of BTX (benzene, toluene, and xylene) isomers, which are major components of gasoline. Likewise, in catalytic pyrolysis of recycled polypropylene, this catalyst generated a higher production of aromatic compounds. Therefore, this catalyst showed excellent performance in generating valuable hydrocarbons of great industrial interest, particularly aromatics.

MnS doping regulating Co active sites on fibrous cobalt nitride as bifunctional oxygen electrocatalyst for high-performance Zn-air battery

Aiming to achieve high-efficiency bifunctional catalysts, doping engineering is applied to construct bifunctional catalysts for oxygen electrodes in Zn-air batteries to strengthen the catalytic kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, MnS doped cobalt nitride catalyst (MnS/CoNx) with divergent fiber morphology is prepared by low temperature nitriding for the self-assembling layered double hydroxides (LDH). The MnS/CoNx shows excellent electrical conductivity and improved catalytic activity on ORR and OER with low overpotential of 290 mV at 10 mA cm−2 and a good half-wave potential of 0.80 V in ORR compared with CoNx and MnO/CoNx. The contribution of the increased bifunctional catalytic performance is possible from the more active center Co3+ and Mn4+, and the elevated electron transport resulted from the opportune high conductive MnS doping. The MnS/CoNx catalyst-driven Zn-air battery achieves a higher power density of 228 mW cm−2 and the excellent long-term stability of 500 h at 20 mA cm−2 far surpassing the commercial Pt/C+RuO2 catalyst.

P-Block anion compressed d/p band center of bifunctional oxygen electrocatalysts for durable aqueous Zn–air batteries

Robust bifunctional electrocatalysts that accelerate the sluggish oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are vital for rechargeable aqueous Zn–air batteries (AZABs). In this study, a three-dimensional foam-like N-doped carbon frameworks (NCFs) catalyst with abundant NCoTe2 active sites (CoTe2@NCFs) was successfully constructed using the carbon dots (CDs)-assisted strategy as the efficient bifunctional ORR/OER catalyst. In situ Raman spectra were used to monitor the formation of Co-OOH, which confirmed the dynamic change in oxygen intermediates on the surface of the CoTe2@NCFs catalyst. Both theoretical calculations and experimental results demonstrate that the integrated Te element in the p-block results in a reduction in the difference between d/p band centers (Δεd-p), which effectively enhances the rapid adsorption/desorption capability of *OOH/*OH, thereby improving the ORR/OER performance. Impressively, the CoTe2@NCFs catalyst shows excellent bifunctional oxygen catalytic performance (ΔE = 0.66 V). Moreover, the assembled CoTe2@NCFs-based rechargeable AZABs exhibit a high peak power density of 177.8 mW cm−2, substantial specific capacity of 793.4 mAh g−1, and excellent long-term cycling durability over 1000 cycles. The compressed d/p-band synergistic center provides novel insights into the design of bifunctional oxygen electrocatalysts for efficient energy storage and conversion devices.

Oxygenate-induced structural evolution of high-entropy electrocatalysts for multifunctional alcohol electrooxidation integrated with hydrogen production

High-entropy compounds have been emerging as promising candidates for electrolysis, yet their controllable electrosynthesis strategy remains a formidable challenge because of the ambiguous ionic interaction and codeposition mechanism. Herein, we report a oxygenates directionally induced electrodeposition strategy to construct high-entropy materials with amorphous features, on which the structural evolution from high-entropy phosphide to oxide is confirmed by introducing vanadate, thus realizing the simultaneous optimization of composition and structure. The representative P-CoNiMnWVOx shows excellent bifunctional catalytic performance toward alkaline hydrogen evolution reaction and ethanol oxidation reaction (EOR), with small potentials of -168 mV and 1.38 V at 100 mA cm-2, respectively. In situ spectroscopy illustrates that the electrochemical reconstruction of P-CoNiMnWVOx induces abundant Co-O species as the main catalytic active species for EOR and follows the conversion pathway of the C2 product. Theoretical calculations reveal the optimized electronic structure and adsorption free energy of reaction intermediates on P-CoNiMnWVOx, thereby resulting in a facilitated kinetic process. A membrane-free electrolyzer delivers both high Faradaic efficiencies of acetate and H2 over 95% and superior stability at100 mA cm-2 during 120 h electrolysis. In addition, the unique composition and structural advantages endow P-CoNiMnWVOx with multifunctional catalytic activity and realize multipathway electrosynthesis of formate-coupled hydrogen production.

Electroless plating of Co[sbnd]P[sbnd]O electrocatalyst on carbon cloth for alkaline water electrolysis

We report the simple method of fabrication, self-supported nanostructure of CoPO nanoparticles (NPs) on carbon cloth scaffold by electroless plating. CoPO demonstrates exceptional bi-functional catalytic performance in water electrolysis, efficiently producing hydrogen (H2) and oxygen (O2) gases simultaneously due to optimized adsorption energy for intermediates and the excellent conductivity of Cobalt-metallic nanoparticles. CoPO achieves a geometric current of 10 mA/cm2 with 190 mV and 280 mV overpotential for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, while its continuous catalytic nanoparticle coating on the carbon cloth scaffold ensures superior charge transport with minimal resistance. It is highly encouraging to observe that the HER and OER performance of CoPO electrodes far surpasses that of carbon cloth, approaching the benchmark set by noble electrocatalysts Pt/C and RuO2. The alkaline electrolyser based on the two-electrode cell using CoPO electrodes demonstrates bi-functional water splitting at 1.64 V and 1.98 V at 10 and 100 mA/cm2. Furthermore, the alkaline electrolyser exhibits stable electrocatalytic activity for about more than 16 h at the current density of 50 mA/cm2.

Cobalt@Ruthenium Core@Shell nanoparticles embedded within nitrogen-doped carbon nanosheets as reversible oxygen electrocatalysts

Rational design and engineering of cost-effective, high-performance reversible oxygen electrocatalysts for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is imperative in advancing the progress of rechargeable metal-air batteries (r-MABs). Herein, nanocomposites based on Co@Ru core@shell nanoparticles embedded within N-doped carbon nanosheets (Co@Ru/CS) are prepared via facile galvanic exchange reactions of RuCl3 with Co/NC and used as an effective oxygen electrocatalyst for rechargeable zinc-air battery (r-ZAB). Electrochemical studies demonstrate a remarkable bifunctional catalytic performance of Co@Ru/CS towards both ORR and OER, featuring a low potential gap (ΔE) of only 0.69 V between the OER potential (E10,OER) at 10 mA cm−2 and half-wave potential (E1/2,ORR) of ORR, which is much lower than that of commercial Pt/C + RuO2 catalysts (0.76 V). Combined studies of experimental characterizations and density functional theory calculations show that the ORR activity arises primarily from the N-doped carbon and CoNx moieties in the composites, whereas RuO2/CoOOH produced at high electrode potentials is responsible for the OER activity. Co@Ru/CS based r-ZAB exhibits an open circuit voltage of 1.447 V, specific capacity of 781 mAh gZn−1, and maximum power density of 115 mW cm−2 at 0.83 V, a performance better than that with commercial Pt/C + RuO2 (1.412 V, 760.56 mAh gZn−1, and 91 mW cm−2). Results from this research underline the substantial impact of structural engineering on optimizing the electrocatalytic activity of nanocomposites for r-MABs.

Optimizing the Dehydrogenation Kinetics of Metal Nitrides for Energy‐Efficient Seawater Hydrogen Production at 2 A cm−2

AbstractSeawater hydrogen production, vital for sustainable energy solutions and freshwater preservation, faces challenges due to seawater complexity and high energy consumption. A strategy to modulate dehydrogenation kinetics of dual‐phase metal nitrides using low‐loaded Pt quantum dots (QDs), achieving stable and energy‐efficient hydrogen generation is introduced. The Pt QDs@Ni3N‐MoN/Ti catalyst displays outstanding bifunctional seawater catalytic performance, enabling efficient hydrogen production and hydrazine degradation in a flow anion exchange membrane water electrolysis (AEMWE) device. Operating at a low voltage of 1.41 V, it achieves 2 A cm−2 for 300 h, circumventing chlorine corrosion and yielding record‐breaking energy equivalent input (2.68 kWh m−3 H2 at 1 A cm−2), a 47.1% reduction compared to traditional methods. Integration with solar and biomass energy facilitates self‐powered hybrid seawater hydrogen production, highlighting its potential applications. This work facilitates energy‐efficient marine resource conversion to green hydrogen and offers viable insights into industrial hazardous pollutant degradation using metal‐nitride electrocatalysts.

Aluminum-induced electron structure on nickel phosphide for effective hydrazine‑assisted water splitting at large current density

Hydrazine-assisted water electrolysis emerges as a promising strategy to replace conventional device for effective hydrogen generation. Limited to the great difference of intermediate adsorption energy for hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR), the design and fabrication of bifunctional catalysts is still a knotty challenge in industrial conditions. Herein, Al-doped Ni2P nanoflower architecture grown in-situ on nickel foam (Al-Ni2P/NF) is fabricated through the combination of hydrothermal process and subsequent phosphorization treatment. Ascribed to the redistribution of electron state and optimization of reaction intermediate energy induced by Al, Al-Ni2P/NF expresses distinguished bifunctional catalytic performance with ultralow potentials of −205 and 300 mV at 500 mA cm−2 for HER and HzOR, respectively. When integrated into hydrazine-assisted water splitting as both the anode and cathode, only 0.717 V is required to reach a large current density of 500 mA cm−2. Specially, a novel integrated system driven entirely by sustainable solar energy is proposed, generating energy-saving hydrogen and purify hydrazine-containing sewage simultaneously. This work provides an attracting and practical path for accelerating the development of hydrogen economy.

Enhanced bifunctional oxygen electrochemical catalytic performance using La-doped CoFe2O4 spinel supported by 3D-G for Zn-air batteries

The preparation of bifunctional catalysts for oxygen reduction (ORR) and oxygen evolution (OER) is crucial for Zn-air batteries. Here, we report a La doped CoFe2O4 spinel catalyst supported on three-dimensional graphene (3D-G), where La can facilitate electron transfer from Co to Fe, leading to increased electron cloud density in Fe and improved catalytic performance. The redshift of the G peak in the Raman spectra indicates the interaction between the π bond of 3D-G and d orbitals in La0.2CoFe1.8O4. La0.2CoFe1.8/3D-G exhibits superior ORR performance (E1/2 = 0.86 V vs. RHE) and OER performance (Ej=10 = 1.55 V vs. RHE) to CoFe2O4/3D-G (E1/2 = 0.831 V vs. RHE, Ej=10 = 1.603 V vs. RHE). Furthermore, it demonstrates excellent bifunctional oxygen catalytic performance while maintaining high power density and stability in liquid zinc-air batteries (ZABs) and flexible ZABs (F-ZABs). This work presents a viable strategy for utilizing rare earth element doped spinels to enhance oxygen catalyst and ZABs performance.

Regulating atomic Fe/Cu dual sites with unsymmetrical Fe-N6 and Cu-N1S2 coordination for promoting bifunctional oxygen electrocatalysis in advanced zinc-air batteries

Dual-metal single-atom catalysts with heteronuclear active sites exhibit superior oxygen catalysis performance than their single-atom counterparts, facilitating the practical applications in advanced electrochemical energy devices. Herein, a Fe-Cu dual-metal single-atom catalyst with Fe-N6 and Cu-N1S2 coordination environment (FeCu-DSAs/NSC) is reported. Due to the synergism of bimetallic active sites and asymmetric heteroatom coordination, the resultant FeCu-DSAs/NSC displays better bifunctional catalytic performance (a small potential gap between the Eη10 and E1/2, ΔE=0.647 V) when compared with the counterparts (Pt/C+IrO2 and Cu-ISAs/NSC), as well as surpassing most of bifunctional metal atom-based catalysts reported to date. As expected, FeCu-DSAs/NSC based rechargeable zinc-air battery shows remarkable superiority than commercial Pt/C+IrO2 benchmark, resulting in a high peak power density (230.66 mW cm−2), open-circuit voltage (1.464 V) and long-term cycling stability (up to 350 h at 10 mA cm−2).

A bifunctional nanoporous gold–copper@ZIF film for highly efficient nitrogen electro-fixation

This work presents a unique electrocatalyst made of nanoporous AuCu alloys incorporated in a ZIF-71 film with bifunctional catalytic performance for electrocatalytic nitrogen fixation.

Interfacial coupling of NiSe in heterostructures promotes electrocatalytic hydrolysis of MoS2.

Molybdenum sulfide (MoS2) has attracted much attention as a potential catalyst for the oxygen evolution reaction (OER), but its unique low activity and low edge active centers limit its electrocatalytic activity. In this study, catalysts were prepared by growing NiSe nanoclusters in situ onto MoS2 substrates via electrodeposition; ultrathin MoS2 nanosheets and NiSe nanoclusters were cross-linked with each other to form a unique three-dimensional rosette structure; and MoS2@NiSe catalysts were successfully synthesised, which significantly improved bifunctional catalytic performance. The synthesised MoS2@NiSe catalysts exhibited good electrochemical performance: overpotentials required to satisfy the HER and OER processes at a current density of 10 mA cm-2 in 1 M KOH were 80 mV and 254 mV, respectively. When applied as a cathode and anode to assemble a bifunctional electrode system, the MoS2@NiSe||MoS2@NiSe electrolytic cell system required only 1.54 V to achieve 10 mA cm-2 in an alkaline electrolyte, which exceeded the value of most of the bifunctional catalysts reported in the literature to date. In addition, the catalyst maintained good surface structure and catalytic performance after a 24 h stability test. This study provides a new idea for the improvement and design of MoS2-based bifunctional catalysts and provides an important reference for research in the field of clean energy.

Dual-strategy engineered nickel phosphide for achieving efficient hydrazine-assisted hydrogen production in seawater.

Electrocatalytic hydrogen production in seawater to alleviate freshwater shortage pressures is promising, but is hindered by the sluggish oxygen evolution reaction and detrimental chloride electrochemistry. Herein, a dual strategy approach of Fe-doping and CeO2-decoration in nickel phosphide (Fe-Ni2P/CeO2) is rationally designed to achieve superior bifunctional catalytic performance for the hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) in seawater. Notably, the two-electrode Fe-Ni2P/CeO2-based hybrid seawater electrolyzer realizes energy-efficient and chlorine-free hydrogen production with ultralow cell voltages of 0.051 and 0.597 V at 10 and 400 mA cm-2, which are significantly lower than those needed in the hydrazine-free seawater electrolyzer. Density functional theory calculations manifest that the combination of Fe doping and heterointerface construction between Fe-Ni2P and CeO2 can adjust the electronic structure of the Ni2P and optimize the water dissociation barrier and hydrogen adsorption free energy, leading to improvement of the intrinsic catalytic performance. This route affords a feasible solution for future large-scale hydrogen generation using abundant ocean water.

Boosted Li₂CO₃ reversible conversion utilizing Cu-doped TiB MBene/graphene for Li-CO₂ batteries

Two-dimensional transition metal borides (MBenes), particularly TiB, hold promise as electrocatalysts for CO₂-related reactions. However, their bifunctional catalytic performance for reversible Li₂CO₃ conversion in Li-CO₂ batteries remains inferior to that...

FeNiCo|MnGaOx Heterostructure Nanoparticles as Bifunctional Electrocatalyst for Zn-Air Batteries.

Driven by the pressing demand for stable energy systems, zinc-air batteries (ZABs) have emerged as crucial energy storage solutions. However, the quest for cost-effective catalysts to enhance vital oxygen evolution and reduction reactions remains challenging. FeNiCo|MnGaOx heterostructure nanoparticles on carbon nanotubes (CNTs) are synthesized using liquid-phase reduction and H2 calcination approach. Compared to its component, such FeNiCo|MnGaOx/CNT shows a high synergistic effect, low impedance, and modulated electronic structure, leading to a superior bifunctional catalytic performance with an overpotential of 255mV at 10mAcm-2 and half-wave potential of 0.824V (ω=1600rpm and 0.1m KOH electrolyte). Moreover, ZABs based on FeNiCo|MnGaOx/CNT demonstrate notable features, including a peak power density of 136.1mWcm-2, a high specific capacity of 808.3mAhgZn -1, and outstanding stability throughout >158h of uninterrupted charge-discharge cycling. Theoretical calculations reveal that the non-homogeneous interface can introduce more carriers and altered electronic structures to refine intermediate adsorption reactions, especially promoting O* formation, thereby enhancing electrocatalytic performance. This work demonstrates the importance of heterostructure interfacial modulation of electronic structure and enhancement of adsorption capacity in promoting the implementation of OER/ORR, ZABs, and related applications.

Metal-Oxygen Covalency Competition of Unsymmetrical Metal Pairs for Enhanced Bifunctional Oxygen Electrocatalysis

Rechargeable zinc-air batteries are considered promising energy conversion devices due to their inherent safety and high energy-to-cost ratio. However, the sluggish kinetics of oxygen evolution reaction and oxygen reduction reaction during the charging-discharging process lead to low round trip efficiency and power density. The synthesis of efficient and stable bifunctional oxygen electrocatalysts constitutes the bottleneck to construct applicable ZABs.Here, we report an Mn-doped ruthenium oxide electrocatalyst that exhibits remarkable ORR/OER activity, with a low potential gap of 0.62V between the half-wave potential of ORR and the OER potential at 10mA cm-2. The Mn-RuO2 assembled ZABs present a high power density of 179 mW cm-2 and long lifespans of 800 h. Metal covalency competition induces surface Mn atoms shows more favorable adsorption behavior for ORR and Ru atoms shows more favorable adsorption behavior for OER. The charge redistribution between asymmetrical Ru-O-Mn pairs results in dual actives sites towards OER/ORR. The surface ruthenium stabilizes the O* intermediate due to the weaker hybridization of the lattice Ru-O bond. The upshift of the dz2 orbital relieves the over-binding of the critical intermediates OH* on the Mn atom. Such dual Ru-Mn sites minimized the OER/ORR activity gap restricted by scaling relationships. Our findings rationalize the double active sites mechanism in Mn-RuO2 electrocatalyst and provide a strategy to enhance bifunctional catalytic performance. Figure 1