Search

CeO2–ZrO2 (CZO) nanoparticles (NPs) have applications in many catalytic reactions, such as methane dry reforming, due to their oxygen cycling ability. Ni doping has been shown to improve the cataly...

Colloidal metal nanoparticles (NPs) have long been regarded as ideal precursors for the synthesis of well-defined supported metal catalysts. However, the integration of colloidal metal NPs and cata...

In this work, ruthenium (Ru) catalysts supported on CeO2 nanorods (NR), nanocubes (NC), and nanoctahedra (NO) were comparatively investigated to correlate the shape and exposed surface planes ({100...

Herein, we report the exploration of understanding the reactivity and structure of atomically dispersed M–N4 (M = Fe and Co) sites for the CO2 reduction reaction (CO2RR). Nitrogen coordinated Fe or Co site atomically dispersed into carbons (M–N–C) containing bulk- and edge-hosted M–N4 coordination were prepared by using Fe- or Co-doped metal–organic framework precursors, respectively, which were further studied as ideal model catalysts. Fe is intrinsically more active than Co in M–N4 for the reduction of CO2 to CO, in terms of a larger current density and a higher CO Faradaic efficiency (FE) (93% vs. 45%). First principle computations elucidated that the edge-hosted M–N2+2–C8 moieties bridging two adjacent armchair-like graphitic layers is the active sites for the CO2RR. They are much more active than previously proposed bulk-hosted M–N4–C10 moieties embedded compactly in a graphitic layer. During the CO2RR, when the dissociation of *COOH occurs on the M–N2+2–C8, the metal atom is the site for the adsorpt...

The sluggish kinetics of methanol oxidation reaction (MOR) is a major barrier to the commercialization of direct methanol fuel cells (DMFCs). In this work, we report a facile synthesis of platinum–ruthenium nanotubes (PtRuNTs) and platinum–ruthenium-coated copper nanowires (PtRu/CuNWs) by galvanic displacement reaction using copper nanowires as a template. The PtRu compositional effect on MOR is investigated; the optimum Pt/Ru bulk atomic ratio is about 4 and surface atomic ratio about 1 for both PtRuNTs and PtRu/CuNWs. Enhanced specific MOR activities are observed on both PtRuNTs and PtRu/CuNWs compared with the benchmark commercial carbon-supported PtRu catalyst (PtRu/C, Hispec 12100). X-ray photoelectron spectroscopy (XPS) reveals a larger extent of electron transfer from Ru to Pt on PtRu/CuNWs, which may lead to a modification of the d-band center of Pt and consequently a weaker bonding of CO (the poisoning intermediate) on Pt and a higher MOR activity on PtRu/CuNWs.

Increased oxygen reduction reaction (ORR) kinetics, improved CO tolerance, and more efficient water and heat management represent significant advantages that high-temperature polymer electrolyte fuel cells (HT-PEFCs) operating with a phosphoric acid-doped polybenzimidazole (PBI) membrane offer over traditional Nafion-based, low-temperature PEFCs. However, before such HT-PEFCs become viable, the detrimental effect of phosphate chemisorption on the performance of state-of-the-art Pt-based cathode catalysts needs to be addressed. In this study, we propose a solution to the severe poisoning of Pt-based PEFC cathode catalysts with phosphates (H2PO4– and HPO42–) by replacing standard Pt/C catalysts with phosphate-tolerant, nonprecious metal catalyst (NPMC) formulations. Catalysts with a very high surface area (845 m2 g–1) were synthesized in this work from polyaniline (PANI), iron, and carbon using a high-temperature approach. The effects of metal precursors and metal loading on the morphology, structure, and O...

Cobalt nanowires (CoNWs) are coated with platinum (Pt) by partial galvanic displacement, forming core/shell wires 200–300 nm in diameter and 100–200 μm in length. Pt-coated CoNWs (PtCoNWs) are characterized for activity in the oxygen reduction reaction (ORR) with rotating disk electrode half-cells in 0.1 M perchloric acid electrolytes. The resulting catalysts demonstrate ORR-specific activities in the range 2053–2783 μA cmPt−2, comparable to the specific activity of polycrystalline Pt. The specific activities of PtCoNWs increase with decreasing Pt content and exhibit a corresponding increase in Pt lattice compression. PtCoNWs have exhibited a maximum mass activity of 793 mA mgPt−1, 2.6 times greater than carbon-supported Pt nanoparticles.

Platinum (Pt)-coated nickel (Ni) nanowires (PtNiNWs) are synthesized by the partial spontaneous galvanic displacement of NiNWs, with a diameter of 150–250 nm and a length of 100–200 μm. PtNiNWs are electrochemically characterized for oxygen reduction (ORR) in rotating disk electrode half-cells with an acidic electrolyte and compared to carbon-supported Pt (Pt/HSC) and a polycrystalline Pt electrode. Like other extended surface catalysts, the nanowire morphology yields significant gains in ORR specific activity compared to Pt/HSC. Unlike other extended surface approaches, the resultant materials have yielded exceptionally high surface areas, greater than 90 m2 gPt–1. These studies have found that reducing the level of Pt displacement increases Pt surface area and ORR mass activity. PtNiNWs produce a peak mass activity of 917 mA mgPt–1, 3.0 times greater than Pt/HSC and 2.1 times greater than the U.S. Department of Energy target for proton-exchange membrane fuel cell activity.