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The electrochemical CO2 reduction reaction (CO2RR) to form highly valued chemicals is a sustainable solution to address the environmental issues caused by excessive CO2 emissions. Generally, it is challenging to achieve high efficiency and selectivity simultaneously in the CO2RR due to multi-proton/electron transfer processes and complex reaction intermediates. Among the studied formulations, bimetallic catalysts have attracted significant attention with promising activity, selectivity, and stability. Engineering the atomic arrangement of bimetallic nanocatalysts is a promising strategy for the rational design of structures (intermetallic, core/shell, and phase-separated structures) to improve catalytic performance. This review summarizes the recent advances, challenges, and opportunities in developing bimetallic catalysts for the CO2RR. In particular, we firstly introduce the possible reaction pathways on bimetallic catalysts concerning the geometric and electronic properties of intermetallic, core/shell, and phase-separated structures at the atomic level. Then, we critically examine recent advances in crystalline structure engineering for bimetallic catalysts, aiming to establish the correlations between structures and catalytic properties. Finally, we provide a perspective on future research directions, emphasizing current challenges and opportunities. [ABSTRACT FROM AUTHOR]

Atomic ordering engineering has been a promising strategy to improve the catalytic activity and stability of Pt-based alloy catalysts for the oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs). However, the synthesis of shape-controlled ordered nanocrystals, especially in a two-dimensional (2D) architecture, still remains a great challenge. Herein, 2D Pd2Sn nanosheets (NSs) with unique Pd–Sn ordering are developed as efficient ORR electrocatalysts for the first time. The ordered Pd2Sn NSs exhibit a mass activity of 2.5 A mgPd−1 at 0.9 ViR-freevs. the reversible hydrogen electrode and outstanding durability, much superior to that of their disordered counterparts, commercial Pt/C, and most of the reported Pd-based ORR catalysts. The outstanding activity and stability can be ascribed to the unique 2D defect-rich morphology, the thermodynamically stabilized intermetallic structure, and the optimized Pd–O binding due to Sn incorporation. [ABSTRACT FROM AUTHOR]

Lithium–sulfur (Li–S) batteries are promising for the next-generation energy storage devices due to their high theoretical energy density and low cost. However, the shuttle effect and the passive layer between the separator and electrode still affect the cycling stability and coulombic efficiency seriously. Herein, we develop a 10 μm-thick rGO (reduced graphene oxide) and molybdenum phosphide (MoP) composite coating layer on a Celgard separator to improve the electrochemical performance of Li–S batteries. The introduction of such a MoP/rGO coating layer on the separator not only impedes the diffusion of polysulfides to the anode but also improves the sulfur utilization. In particular, the 10 nm MoP nanoparticles are very efficient for the polysulfide adsorption. Compared to the pristine Celgard separator, superior electrochemical performance is obtained in both coin cells and pouch cells with the MoP/rGO coated separator. High areal capacity (∼3 mA h cm−2), good rate performance, and long cycle life (300 cycles) are attained under a sulfur loading of 3.88 mg cm−2. The capacity decay rate is as low as 0.045% per cycle over 300 cycles. In addition, the pouch cells made by the modified separator with a high sulfur loading of 4.6 mg cm−2 achieve good electrochemical performance. At 0.1C, the initial discharge capacity is 1083 mA h g−1, and still remains at 759 mA h g−1 after 120 cycles. The result reveals the potential practical use of this MoP/rGO coated separator for Li–S batteries. [ABSTRACT FROM AUTHOR]

Transition metal phosphides are often studied as hydrogen evolution reaction cathode catalysts, but scarcely as oxygen evolution reaction (OER) anode catalysts for water oxidation. Herein, we report a new amorphous Co0.63Fe0.21P0.16 OER catalyst, which was prepared through a one-step solvothermal process. This catalyst exhibits extraordinary OER catalytic activity in alkaline media and is superior to the state of the art IrO2 in 1.0 M KOH, capable of yielding a current density of 10 mA cm−2 at an overpotential of only 217 mV. This newly achieved high activity outperforms most reported transition metal phosphide catalysts. During the OER, the surface layers of the Co0.63Fe0.21P0.16 nanospheres (200–500 nm) are oxidized, which show the typical Tafel slope of oxides around 40 mV dec−1. The in situ formation of surface Co oxides in the catalysts during the OER along with an optimal doping of Fe are found to be crucial for their remarkable activity. In particular, the metal-rich amorphous phosphide cores, i.e., substrates, probably contribute to OER performance of the catalysts due to their high electrical conductivity. This new type of surface oxidized amorphous transition metal phosphide would provide a new pathway for the design of high-performance OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Molybdenum disulfide (MoS2) is a promising catalyst for hydrogen generation from water splitting. However, there is still a gap compared to electrocatalytic performance of Pt group metals. Herein, we propose a simple solvothermal method to prepare ultrasmall MoS2–Au nanohybrids with average diameters of 2.5 nm. The MoS2–Au nanohybrids exhibit superior HER performance with a low onset potential of 17 mV, a Tafel slope of 40 mV dec−1 and a current density of 10 mA cm−2 at an overpotential of only 66 mV. The enhanced HER catalytic activity is attributed to the doping of gold resulting in a synergistic effect between Au and MoS2, which promotes the activity of the edge sites and enhancement of conductivity. Our work has provided a new approach to synthesize hybridized MoS2 for an enhanced hydrogen evolution reaction (HER). [ABSTRACT FROM AUTHOR]

Transition metal phosphides like CoP, MoP, Ni2P are suggested to be highly efficient catalysts for hydrogen evolution reaction (HER). However, HER-inert oxides would usually form on the surfaces of these phosphides during preparation and long-term storage. In this study, a simple combination method of grinding and electrochemical activation is used to tune the surface states of long-term stored commercial MoP microparticles, which show low activity for HER due to the molybdenum and phosphorus oxides on the surface, resulting in more exposed active sites of MoP and an enhanced catalytic activity for HER with an onset potential of 0.08 V vs. RHE and a Tafel slope of 50 mV dec−1. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) to form highly valued chemicals is a sustainable solution to address the environmental issues caused by excessive CO2 emissions. Generally, it is challenging to achieve high efficiency and selectivity simultaneously in the CO2RR due to multi-proton/electron transfer processes and complex reaction intermediates. Among the studied formulations, bimetallic catalysts have attracted significant attention with promising activity, selectivity, and stability. Engineering the atomic arrangement of bimetallic nanocatalysts is a promising strategy for the rational design of structures (intermetallic, core/shell, and phase-separated structures) to improve catalytic performance. This review summarizes the recent advances, challenges, and opportunities in developing bimetallic catalysts for the CO2RR. In particular, we firstly introduce the possible reaction pathways on bimetallic catalysts concerning the geometric and electronic properties of intermetallic, core/shell, and phase-separated structures at the atomic level. Then, we critically examine recent advances in crystalline structure engineering for bimetallic catalysts, aiming to establish the correlations between structures and catalytic properties. Finally, we provide a perspective on future research directions, emphasizing current challenges and opportunities.

Antimony (Sb) based materials are regarded as promising anode materials for Li-ion batteries (LIBs) because of the high capacity, appropriate working potential, and earth abundance of antimony. However, the quick capacity decay due to the huge volume expansion during the cycling process seriously hinders its practical applications. Here, a nanocomposite of core@shell Sb@Sb 2 O 3 particles anchored on 3D porous nitrogen-doped carbon (3DNC) nanosheets is synthesized by freeze drying and sintering in a reducing atmosphere. Structural characterization shows that the developed Sb@Sb 2 O 3 /3DNC electrode has a high surface area (839.8 m 2 g -1 ) and unique Sb-O-C bonding, both contributing to the excellent electrochemical performance. The initial charge and discharge specific capacities of the Sb@ Sb 2 O 3 /3DNC anode in LIB tests are 1109 mA h g -1 and 1810 mA h g -1 , respectively. Also, it shows a charge capacity of 696.9 mA h g -1 after 500 cycles at 1 A g -1 and 458 mA h g -1 at a current density of 5 A g -1 . Moreover, the assembled Sb@Sb 2 O 3 /3DNC‖LiNi 0.6 Co 0.2 Mn 0.2 O 2 battery exhibits a discharge capacity of more than 100 mA h g -1 after 25 cycles at 100 mA g -1 . The synthetic method can be extended to obtain other nanocomposites of metal and carbon materials for high-performance energy storage devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)