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Comprehensive Summary: Liquid fed fuel cells such as direct formic acid fuel cells (DFAFCs) are considered to be promising power sources for portable electronic devices. However, the poison of CO intermediates on the state‐of‐the‐art platinum and palladium‐based electrocatalysts for the formic acid oxidation reaction (FAOR) at the anode hampers the implementation of DFAFCs technologies. Here, we report a core/shell catalyst consisting of intermetallic PdCd core and Pd shell (i‐PdCd@Pd) with promoted CO anti‐poison ability and thus FAOR performance. The optimal i‐PdCd@Pd catalyst exhibits a high mass activity and specific activity at peak potential, which are 24 and 4 times greater than that of commercial Pd/C catalyst, respectively. We understand by in‐situ surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRA) and X‐ray photoelectron spectroscopy (XPS) that in i‐PdCd@Pd, the intermetallic PdCd under‐layers can induce the downshift of d‐band center of surface Pd atoms, which would improve the CO tolerance and thus promote the FAOR performance. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Liquid fed fuel cells such as direct formic acid fuel cells (DFAFCs) are considered to be promising power sources for portable electronic devices. However, the poison of CO intermediates on the state‐of‐the‐art platinum and palladium‐based electrocatalysts for the formic acid oxidation reaction (FAOR) at the anode hampers the implementation of DFAFCs technologies. Here, we report a core/shell catalyst consisting of intermetallic PdCd core and Pd shell (i‐PdCd@Pd) with promoted CO anti‐poison ability and thus FAOR performance. The optimal i‐PdCd@Pd catalyst exhibits a high mass activity and specific activity at peak potential, which are 24 and 4 times greater than that of commercial Pd/C catalyst, respectively. We understand by in‐situ surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRA) and X‐ray photoelectron spectroscopy (XPS) that in i‐PdCd@Pd, the intermetallic PdCd under‐layers can induce the downshift of d‐band center of surface Pd atoms, which would improve the CO tolerance and thus promote the FAOR performance. [ABSTRACT FROM AUTHOR]

The development of highly efficient electrocatalysts for complete oxidation of ethylene glycol (EG) in direct EG fuel cells is of decisive importance to hold higher energy efficiency. Despite some achievements, their progress, especially electrocatalytic selectivity to complete oxidated C 1 products, is remarkably slower than expected. In this work, we developed a facile aqueous synthesis of Ir-doped CuPd single-crystalline mesoporous nanotetrahedrons (Ir-CuPd SMTs) as high-performance electrocatalyst for promoting oxidation cleavage of C-C bond in alkaline EG oxidation reaction (EGOR) electrocatalysis. The synthesis relied on precise reduction/co-nucleation and epitaxial growth of Ir, Cu and Pd precursors with cetyltrimethylammonium chloride as the mesopore-forming surfactant and extra Br - as the facet-selective agent under ambient conditions. The products featured concave nanotetrahedron morphology enclosed by well-defined (111) facets, single-crystalline and mesoporous structure radiated from the center, and uniform elemental composition without any phase separation. Ir-CuPd SMTs disclosed remarkably enhanced electrocatalytic activity and excellent stability as well as superior selectivity of C 1 products for alkaline EGOR electrocatalysis. Detailed mechanism studies demonstrated that performance improvement came from structural and compositional synergies, which kinetically accelerated transports of electrons/reactants within active sites of penetrated mesopores and facilitated oxidation cleavage of high-energy-barrier C-C bond of EG for desired C 1 products. More interestingly, Ir-CuPd SMTs performed well in coupled electrocatalysis of anode EGOR and cathode nitrate reduction, highlighting its high potential as bifunctional electrocatalyst in various applications., (© 2024 Wiley‐VCH GmbH.)

Enhancing catalytic performance as well as reducing catalyst cost are the eternal pursuit for the catalysis community. Herein, a simple and effective palladium-doped cobalt (Pd/Co) catalyst with high Pd atom utilization efficiency was synthesized via galvanic replacement reaction for the selective hydrogenation of nitrobenzene with H 2 at room temperature, delivering >99 % yield of aniline with up to 158 times higher catalytic activity than commercial palladium powder. Detailed characterizations and DFT calculations revealed that Co-Pd interaction leads to a decrease in electron density of Pd and the distance between Pd atoms that results in the enhanced catalytic performance. Further experiments indicated that the Pd/Co catalyst serves as a highly efficient, selective, and recyclable catalyst for a range of nitroarene substrates. This work might provide a green and sustainable methodology to design and synthesize highly active catalysts with high utilization efficiency of the noble metals in fundamental and applied research., (© 2022 Wiley-VCH GmbH.)

Rh catalysts exhibit unexpected high activity for the methanol oxidation reaction (MOR) in alkaline conditions, making them potential anodic catalysts for direct methanol fuel cells (DMFCs). Nevertheless, the MOR mechanism on Rh electrodes has not been clarified thus far, which impedes the development of high-efficiency Rh-based MOR catalysts. To investigate it, a combination of in situ electrochemical techniques called attenuated total refection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and infrared reflection absorption spectroscopy (IRAS) is used. Cyclic voltammograms of MOR at Rh electrodes show considerable activity in alkaline media rather than acidic media, although the real-time ATR-SEIRA spectral results demonstrate that methanol can rarely self-decompose on Rh at open-circuit conditions. Meanwhile, in combination of ATR-SEIRAS and IRAS results, CO 2 and formate are thought to be MOR products, suggesting a dual-pathway mechanism ("CO 2 pathway" and "formate pathway"). Specifically, CO ad species, which are the major intermediates in the CO 2 pathway, can produce at lower potentials and be oxidized into CO 2 at a potential of 0.5-0.75 V. Concurrently, the formate can be produced from 0.5 V and diffuse into the bulk electrolyte to become one of the MOR products, while the further electrochemical conversion of formate to CO 2 is essentially negligible. More directly, the apparent selectivity ( r ) of the CO 2 pathway is estimated to reach ca. 0.63 at 0.9 V, confirming the potential-dependent selectivity of MOR at Rh surfaces. This study might provide fresh insights into the design and fabrication of effective Rh-based catalysts for MOR.