Showing papers by "Bingbing Chen published in 2021"

A stable low-temperature H2-production catalyst by crowding Pt on α-MoC.

Abstract: The water–gas shift (WGS) reaction is an industrially important source of pure hydrogen (H2) at the expense of carbon monoxide and water1,2. This reaction is of interest for fuel-cell applications, but requires WGS catalysts that are durable and highly active at low temperatures3. Here we demonstrate that the structure (Pt1–Ptn)/α-MoC, where isolated platinum atoms (Pt1) and subnanometre platinum clusters (Ptn) are stabilized on α-molybdenum carbide (α-MoC), catalyses the WGS reaction even at 313 kelvin, with a hydrogen-production pathway involving direct carbon monoxide dissociation identified. We find that it is critical to crowd the α-MoC surface with Pt1 and Ptn species, which prevents oxidation of the support that would cause catalyst deactivation, as seen with gold/α-MoC (ref. 4), and gives our system high stability and a high metal-normalized turnover number of 4,300,000 moles of hydrogen per mole of platinum. We anticipate that the strategy demonstrated here will be pivotal for the design of highly active and stable catalysts for effective activation of important molecules such as water and carbon monoxide for energy production. A stable, low-temperature water–gas shift catalyst is achieved by crowding platinum atoms and clusters on α-molybdenum carbide; the crowding protects the support from oxidation that would cause catalyst deactivation.

Highly active sites of low spin Fe II N 4 species: The identification and the ORR performance

Abstract: Over recent years, catalytic materials of Fe-N-C species have been recognized being active for oxygen reduction reaction (ORR). However, the identification of active site remains challenging as it generally involves a pyrolysis process and mixed components being obtained. Herein Fe3C/C and Fe2N/C samples were synthesized by temperature programmed reduction of Fe precursors in 15% CH4/H2 and pure NH3, respectively. By acid leaching of Fe2N/C sample, only single sites of FeN4 species were presented, providing an ideal model for identification of catalytic functions of the single sites of FeN4 in ORR. A correlation was conducted between the concentration of FeIIN4 in low spin state by Mossbauer spectra and the kinetic current density at 0.8 V in alkaline media, and such a structure-performance correlation assures the catalytic roles of low spin FeIIN4 species as highly active sites for the ORR.

α-MoC1−x nanorods as an efficient hydrogen evolution reaction electrocatalyst

Abstract: As one class of efficient non-precious metal catalysts for the hydrogen evolution reaction (HER), molybdenum carbides have attracted much attention in recent decades. Efforts have been devoted to the structure and phase modulation to further enhance their performances in the HER. In this study, owing to its superior capability for H2O dissociation, a pure phase of α-MoC1−x with an fcc structure was synthesized, which proved to be more active than β-Mo2C with an hcp structure for H2 evolution. To further improve the electrocatalytic activity, porous α-MoC1−x nanorods were synthesized via controlled carburization of MoO3 nanorod precursors. Benefiting from their more exposed active sites and facilitated mass and charge transfer, α-MoC1−x nanorods exhibited significantly enhanced HER performance under both acidic and alkaline conditions, paving the way for α-MoC1−x as effective electrocatalysts for hydrogen evolution reactions.

Cerium-titanium composite nanorod catalyst for fixed source flue gas denitration reaction and preparation method thereof

Abstract: The invention provides an ammonia selective catalytic reduction nitrogen oxide catalyst for fixed source flue gas denitration, a preparation method and application of the ammonia selective catalytic reduction nitrogen oxide catalyst. The catalyst comprises a carrier and an active component; the carrier is a cerium-titanium composite nanorod; wherein the active component is a transition metal oxideor a combination of the transition metal oxide and a rare earth metal oxide, and the transition metal oxide is manganese oxide; the rare earth metal oxide is samarium oxide; wherein the specific surface area of the cerium-titanium composite nanorod is greater than or equal to 300 square meters per gram. The cerium-titanium composite oxide is made into the macroscopic morphology of the nanorod, sothat the dispersion of active components is facilitated while the specific surface area of the material is increased; when the active components are loaded, a precipitant is firstly added, and then asalt solution of the active components is added, so that in the prepared catalyst, the dispersity of the active components is remarkably improved, and the catalytic activity is improved.