Core-shell Electrocatalysts Research Articles

Electro-Oxidation of Glycerol on Core–Shell M@Pt/C (M = Co, Ni, Sn) Catalysts in Alkaline Medium

This study explores the development of core–shell electrocatalysts for efficient glycerol oxidation in alkaline media. Carbon-supported M@Pt/C (M = Co, Ni, Sn) catalysts with a 1:1 atomic ratio of metal (M) to platinum (Pt) were synthesized using a facile sodium borohydride reduction method. The analysis confirmed the formation of the desired core–shell structure, with Pt dominating the surface as evidenced by energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) revealed the presence of a face-centered cubic (fcc) Pt structure for Co@Pt/C and Ni@Pt/C. Interestingly, Sn@Pt/C displayed a PtSn alloy formation indicated by shifted Pt peaks and the presence of minor Sn oxide peaks. Notably, no diffraction peaks were observed for the core metals, suggesting their amorphous nature. Electrocatalytic evaluation through cyclic voltammetry (CV) revealed superior glycerol oxidation activity for Co@Pt/C compared to all other catalysts. The maximum current density followed the order Co@Pt/C > Ni@Pt/C > Sn@Pt/C > Pt/C. This highlights the effectiveness of the core–shell design in enhancing activity. Furthermore, Sn@Pt/C displayed remarkable poisoning tolerance attributed to a combined effect: a bifunctional mechanism driven by Sn oxides and an electronic effect within the PtSn alloy. These findings demonstrate the significant potential of core–shell M@Pt/C structures for designing highly active and poisoning-resistant electrocatalysts for glycerol oxidation. The presented approach paves the way for further development of optimized catalysts with enhanced performance and stability aiming at future applications in direct glycerol fuel cells.

Achieving advanced hydrogen evolution under large current density using an amorphous/crystalline core-shell electrocatalyst of a-NiCoP/Co2P.

Non-precious transition metal-based electrocatalysts with high activities are promising candidates for substituting Pt- or Ru-based electrocatalysts in hydrogen evolution. In this study, we propose core-shell engineering to combine the amorphous NiCoP and crystalline Co2P (a-NiCoP/Co2P@NF), which requires an ultra-low overpotential of only 26 mV to achieve the benchmark current density of 10 mA cm-2. Furthermore, it achieves an industrial-level hydrogen evolution current density of 500 mA cm-2 with excellent stability. The superior catalytic performance and stability can be attributed to the hierarchical amorphous/crystalline interface and the electron-rich interfacial Co sites. The amorphous NiCoP shell can not only protect the internal Co2P from corrosion, but also provide a larger electrochemically active area. Together, the Co2P core provides fast electron transport and promotes H2 emission from the interfacial electron-rich Co sites. This work provides inspiration to the rational design of an advanced core-shell structure between amorphous and crystalline states.

Fe-Rich Medium-Entropy Core-Shell Electrocatalyst for Hydrogen Evolution Reaction Under Large Current Density.

In response to the low stability of expensive Pt under large current, exploring the stable, efficient and cost-competitive electrocatalyst for hydrogen evolution reaction is crucial for advancing green hydrogen production. Here, a strategy relating to constructing the core-shell structure with near-zero-resistance homogeneous interface is applied to synthesize new Fe-rich medium-entropy alloy (MEA) catalyst. This low-cost sample presents both outstanding durability and catalytic activity with an overpotential of 343.6mV at 1,000mAcm-2 as well as Tafel slope of 67.6mVdec-1, respectively much lower than benchmark catalyst 20%Pt/C (416.9mV, 156.8mVdec-1) in 1.0m KOH solution. Such properties are attributed to the enhanced reactivity of surface active sites with electrons easy injection from MEA metallic core to MEO (medium entropy oxide) shell via their highly conductive homogeneous interface. In MEO layer, Fe/Ni/Co sites are identified as active centres and their high oxidation is crucial to shift themselves toward deep energy, weakening Metal─H bonding and thereby accelerating hydrogen evolution. This work not only exploits one novel electrocatalyst suitable for industrial high-current environments but also provides broad application prospects for MEA utilization.

3D Pt@ZnAl-LDH catalyst on low-grade charcoal: A novel electrochemical platform for efficient textile dye degradation and glycerol oxidation

The development of sustainable and efficient electrochemical processes is crucial for addressing global challenges related to water scarcity. In this study, we present a novel 3D core-shell electrocatalyst, Pt@ZnAl-LDH, supported on low-grade charcoal (LGC), which exhibits exceptional electrocatalytic activity for the degradation and decolorization of dye and the electrocatalytic conversion of glycerol to valuable C3 chemicals. The electrocatalytic degradation of methylene blue dye from water was investigated with a focus on the impact of temperature, pH, and dye concentration. The Pt@ZnAl-LDH/LGC anode demonstrates high selectivity for converting glucose into lactate and other C3 products, achieving an impressive 85% conversion rate at 0.5V vs. Furthermore, the electrode achieves an exceptionally high level of selectivity for C3 products, reaching 86% at 2.2V vs, significantly outperforming other electrodes. Theoretical calculations and electrochemical in situ techniques reveal that the incorporation of ZnAl-LDH enhances the adsorption of hydroxyl species, leading to improved glucose oxidation reaction performance. The 3D Pt@ZnAl-LDH/LGC catalyst optimizes glycerol adsorption, preventing the formation of unwanted intermediates and ensuring high activity and selectivity for C3 products. This work presents a novel electrocatalytic compound for the degradation of toxic dyes and the production of valuable C3 products using an inexpensive aqueous glucose oxidation method.

Composite shell empowered crystalline-amorphous NiO/NiWO4-rGO core-shell electrocatalyst for efficient water electrocatalysis

Composite shell empowered crystalline-amorphous NiO/NiWO4-rGO core-shell electrocatalyst for efficient water electrocatalysis

Improved Alcohol Oxidation through Combined Effects of Tensile Lattice Strain and Twin Defects in Core-Shell Electrocatalysts.

The direct alcohol fuel cells (DAFCs) rely on alcohol oxidation reactions (AORs) to produce electricity, which require catalysts with optimized electronic structure to accelerate the sluggish AORs. Herein, an epitaxial growth of Pd layer onto the pentatwinned Au@Ag core-shell nanorods (NRs) is reported to synthesize highly strained Au@AgPd core-shell NRs. The tensile strain in the AgPd shell of the Au@AgPd nanorods (NRs) arises not only from the core-shell lattice mismatch but also from twinning and lattice distortion occurring at the five twinned boundaries present in the structure. Theoretical simulations prove that the presence of tensile strains in the AgPd layer leads to a significant upward shift of the d-band center of the Pd site toward the Fermi level which remarkably changes the adsorption energy of alcohols on the surface. Highly strained Au@AgPd NRs show exceptional mass activities in electrochemical oxidation of biomass-derived alcohols (ethylene glycol, ethanol, and glycerol) reaching up to 18.66, 15.6, and 7.90 A mgpd -1, respectively. These values are 23.3, 23.6, and 23.2 times higher than commercial Pd/C catalysts. This strain engineering strategy set the platform for the design and synthesis of highly efficient and versatile catalysts for the construction of high-performance DAFCs.

A Coherent Pd–Pd16B3 Core–Shell Electrocatalyst for Controlled Hydrogenation in Nitrogen Reduction Reaction

AbstractThe manipulation of surface catalytic sites has rarely been explored for metal borides, and the subsurface effects on the electrocatalytic activity of the nitrogen reduction reaction (NRR) remain unknown. Herein, this work develops a core–shell nanoparticle catalyst with a Pd core that ensures high electron transfer rates and an Pd16B3 atomical shell that possess tunable active sites for regulating the NRR. The atomic structural evolution from Pd to Pd16B3 is investigated by precisely controlling the B atom diffusion, molecular rearrangement, and d–sp orbital hybridization. Pd/Pd16B3 core–shell nanocrystals exhibit an exceptional NRR performance with a high NH3 Faradaic efficiency of 30.8%, which is superior to those of pristine Pd (1.2%) and B‐doped Pd (4.8%) under identical conditions, and a yield rate of 0.81 µmol h−1 cm−2. This work discovers that the Pd16B3 shell could promote the NRR selectivity by separating the separating the hydrogen evolution reaction proceeded on hole sites and NRR proceeded on bridge sites, and the Pd core could provide the excellent conductivity to Pd16B3 shell through regulated electron interactions. Consequently, the controlled chemical ordering of palladium boride on palladium surfaces provides insight into the synthesis of advanced NRR electrocatalysts.

An efficient cathode electrocatalyst for anion exchange membrane water electrolyzer

An efficient cathode electrocatalyst for anion exchange membrane water electrolyzer

Enhanced full-seawater splitting with a CoNiP@N,P-C core-shell electrocatalyst.

This study investigated a novel electrocatalyst with a core-shell structure of CoNiP@N,P-C. The unique carbon shell of this catalyst serves a dual purpose: exposing numerous active sites and safeguarding CoNiP nanoparticles from dissolution caused by the electrolyte. As a result, the CoNiP@N,P-C nanoparticles exhibit exceptional electrochemical properties. The CoNiP@N,P-C catalyst displays overpotentials of 234 and 314 mV for the HER and OER, respectively, within a simulated seawater solution (1 M KOH + 0.5 M NaCl), indicating its outstanding catalytic performance. Moreover, when subjected to full seawater splitting, the CoNiP@N,P-C catalyst exhibited high activity, achieving a 1.71 V cell voltage at a current density of 10 mA cm-2. As revealed by density functional theory (DFT) calculations, the CoNiP@N,P-C catalyst exhibits Gibbs free energy for hydrogen adsorption (ΔGH* = -0.19 eV) that is decreased in comparison with CoP@N,P-C, NiP@N,P-C, and N,P-C (-0.321 eV, -0.434 eV, and 0.723 eV, respectively). This finding confirms that the core-shell structure plays a role in enhancing the HER kinetics and improving the catalytic performance, which is consistent with the experimental observations. Consequently, this study introduces the concept of utilizing bimetal phosphide core-shell structures for overall seawater splitting, offering a novel approach in this field of research.

The effects of the core material (M = Co, Ni) and catalyst support (N = MWCNTs and rGO) on the performance of M@Pd/N core–shell electrocatalysts for formate oxidation and direct formate-hydrogen peroxide fuel cells

The obtained results show that the presence of Ni at the core instead of Co and using rGO as catalyst support instead of MWCNTs increased the catalytic performance of the synthesized electrocatalyst towards formate oxidation.

Improving Alkaline Hydrogen Oxidation through Dynamic Lattice Hydrogen Migration in Pd@Pt Core-Shell Electrocatalysts.

Tracking the trajectory of hydrogen intermediates during hydrogen electro-catalysis is beneficial for designing synergetic multi-component catalysts with division of chemical labor. Herein, we demonstrate a novel dynamic lattice hydrogen (LH) migration mechanism that leads to two orders of magnitude increase in the alkaline hydrogen oxidation reaction (HOR) activity on Pd@Pt over pure Pd, even ≈31.8 times mass activity enhancement than commercial Pt. Specifically, the polarization-driven electrochemical hydrogenation process from Pd@Pt to PdHx @Pt by incorporating LH allows more surface vacancy Pt sites to increase the surface H coverage. The inverse dehydrogenation process makes PdHx as an H reservoir, providing LH migrates to the surface of Pt and participates in the HOR. Meanwhile, the formation of PdHx induces electronic effect, lowering the energy barrier of rate-determining Volmer step, thus resulting in the HOR kinetics on Pd@Pt being proportional to the LH concentration in the in situ formed PdHx @Pt. Moreover, this dynamic catalysis mechanism would open up the catalysts scope for hydrogen electro-catalysis.

(Invited) Designing Advanced Low-PGM Core-Shell Electrocatalysts for Fuel Cells and Electrolyzers

The low-content Pt-based core-shell catalysts potentially alleviate the drawback in the existing Pt catalysts (i.e., high cost, slow kinetics, poor stability, etc.) and further improve the oxygen reduction reaction (ORR) activity and stability for the proton exchange membrane fuel cells (PEMFCs).1 There have been remarkable advances in both the development of promising core−shell catalysts and the understanding of the fundamental catalytic mechanisms, and it is clear that some of the low platinum-group-metal (PGM) core−shell catalysts with enhanced activity and stability have great potential for use in PEMFCs. Nevertheless, various issues still need to be clearly addressed for the advanced core−shell catalysts of the future. On the other hand, PEM electrolyzers (ELs) are desirable large-scale energy devices to produce green hydrogen toward a net-zero carbon economy. The technologies require the availability of effective catalysts, particularly for the oxygen evolution reaction (OER). However, Ir- and Ru-based catalysts are currently the best-performing OER catalysts and their cost and limited availability hamper the widespread commercialization/deployment of PEMELs. Therefore, there is also an urgent need for developing highly durable and inexpensive catalysts for the OER. This talk first focuses on synthetic strategies, catalytic mechanisms, and influencing factors of Pt- and Ir-based catalysts used for PEMFCs and PEMELs. We will then discuss effective and solid strategies/designs to employ transition-metal-nitride-based cores for the development of highly advanced low-PGM core-shell catalysts for the ORR, particularly in heavy-duty vehicle (HDV) PEMFC applications, and for the OER in PEMEL applications. R. Zhao and K. Sasaki, Advanced Pt-Based Core-Shell Electrocatalysts for Fuel Cell Cathodes, Accounts of Chemical Research. 55 (2022) 1226-1236.

Highly active and durable core–shell electrocatalysts for proton exchange membrane fuel cells

Highly active and durable core–shell electrocatalysts for proton exchange membrane fuel cells

MOFs derived N doped CuNix@C dual metallic core-shell electrocatalysts for CO2 electrocatalytic reduction

MOFs derived N doped CuNix@C dual metallic core-shell electrocatalysts for CO2 electrocatalytic reduction

Cation defect engineering of core–shell spinels nanoelectrocatalyst for enhanced oxygen evolution reaction

Defect engineering is a promising approach to address the inherently low conductivity and limited number of reaction sites of manganese-based spinel oxides as electrocatalysts. However, high formation energies make it challenging to controllably generate cation defects in such spinel oxides. Herein, we report a heterogeneous core–shell electrocatalyst [Mn3O4@MnxCo3−xO4–Co2(OH)3Cl, MCIL] based on a facile cation-deficiency strategy. The addition of ionic liquid (1-butyl-3-methylimidazole hexafluorophosphate) to the reaction system can simply and quickly control the octahedral field defects in spinel MnCo2O4. The results show that the selective generation of defects in the Co(Oh) octahedral field can accelerate the OER reaction kinetics and provide excellent OER electrocatalytic performance. Specifically, the MCIL series catalysts can exhibit the lowest overpotential of 332 mV at 10 mA cm−2 and Tafel slope of 50 mV dec−1, compared with that of pristine samples [i.e., Mn3O4 (890 and 343 mV dec−1) and Mn3O4@MnCo2O4 (357 and 56 mV dec−1)]. This work highlights the importance of cation defect engineering to enhance the catalytic activity of materials.

Nickel phosphide nanoarrays decorated on amorphous NiPOx/Fe(OH)3: A stable core–shell electrocatalyst for efficient oxygen evolution at large current density

Nickel phosphide nanoarrays decorated on amorphous NiPOx/Fe(OH)3: A stable core–shell electrocatalyst for efficient oxygen evolution at large current density

Interfaces coupling of Co8FeS8-Fe5C2 with elevated d-band center for efficient water oxidation catalysis

Interfaces coupling of Co8FeS8-Fe5C2 with elevated d-band center for efficient water oxidation catalysis

Electrocatalytic selectivity to H2O2 enabled by two-electron pathway on Cu-deficient Au@Cu2-xS-CNTs electrocatalysts

• The Au@Cu 2-x S electrocatalysts with different content of Cu defects are systematically explored. • The correlation between the Cu defect and selectivity of H 2 O 2 is established. • The catalyst with the richest Cu defects exhibits excellent H 2 O 2 yield and stability. • The reaction mechanism is revealed by DFT calculations and experimental investigations. Electrochemical hydrogen peroxide (H 2 O 2 ) production by two-electron oxygen reduction reaction (ORR) is an efficient and promising method to alternate industrial anthraquinone process. Herein, the Cu-deficient Au@Cu 2-x S-CNTs core–shell electrocatalysts were synthesized for two-electron ORR, and composition, surface and structural properties were investigated using physicochemical characterizations. The Cu-defective Au@Cu 2-x S-CNTs catalysts exhibit higher catalytic ORR activity and H 2 O 2 specific productivity than Au@Cu 2 O-CNTs, indicating that the introduction of Cu defects effectively improves the two-electron transfer of ORR. The composition-optimized Au@Cu 1.75 S-CNTs sample with the abundant Cu defects exhibits high H 2 O 2 selectivity (∼94 %) and good stability. Theoretical calculations reveal that the introduction of Cu defects can significantly lower the reaction energy barrier of the determinant intermediate OOH* formation of two-electron ORR pathway. This endows the synthesized catalysts with improved resistance to H 2 O generation. Our work deepens the fundamental understanding for guiding the optimization of H 2 O 2 electrosynthesis catalysts to enhance selectivity and efficiency of two-electron pathway.

Engineering Amorphous/Crystalline Rod-like Core-Shell Electrocatalysts for Overall Water Splitting.

The design of bifunctional electrocatalysts for hydrogen and oxygen evolution reactions delivering excellent catalytic activity and stability is highly desirable, yet challenged. Herein, we report an amorphous RuO2-encapsulated crystalline Ni0.85Se nanorod structure (termed as a/c-RuO2/Ni0.85Se) for enhanced HER and OER activities. The as-prepared a/c-RuO2/Ni0.85Se nanorods not only demonstrate splendid HER activity (58 mV@10 mA cm-2 vs RHE), OER activity (233 mV@10 mA cm-2 vs RHE), and electrolyzer activity (1.488 V@10 mA cm-2 vs RHE for overall water splitting) but also exhibit long-term stability with negligible performance decay after 50 h continuous test for overall water splitting. In addition, the variation of the d-band center (from the perspective of bonding and antibonding states) is unveiled theoretically by density functional theory calculations upon amorphous RuO2 layers coupling to clarify the increased hydrogen species adsorption for HER activity enhancement. This work represents a new pathway for the fabrication of bifunctional electrocatalysts toward green hydrogen generation.

Hierarchical core-shell Cu(OH)2@CoS/CF nanoarrays for electrocatalytic water oxidation

The oxygen evolution reaction (OER) is accompanied by four-electron transfer, and its slow reaction kinetics seriously hinders the large-scale application of water electrolysis technology. Therefore, there is an urgent need to develop a non-noble metal catalyst with excellent catalytic performance, good stability, and low price. In this study, we utilize interface engineering and morphology engineering strategies to electrodeposit CoS nanosheets on Cu(OH) 2 nanorods to form three-dimensional hierarchical core-shell electrocatalysts, which could not only provide a large electrochemically active surface area and expose more active sites, but also facilitate electrolyte diffusion and gas product release. The catalyst exhibits good electrocatalytic activity with an overpotential of only 321 mV at a current density of 100 mA cm −2 and a stable operation of 40 h at an overpotential of 280 mV. This study provides a simple method for rapidly preparing electrocatalysts with layered core-shell nanoarray structures. • The preparation method is simple and rapid. • Cu(OH) 2 @CoS/CF electrode with core-shell nanoarray structure was prepared. • It offered a current density of 100 mA cm -2 with only an overpotential of 321 mV. • The catalyst worked stably for 40 h at an overpotential of 280 mV.