https://doi.org/10.1016/j.xinn.2022.100281

Metal-organic framework nanocrystal-derived hollow porous materials: Synthetic strategies and emerging applications

Developing efficient electrocatalysts is of significance for hydrogen production in acid electrolyte. In this work, we report a facile decoration of ruthenium species onto tungsten oxides to construct the Mott-Schottky heterojunction electrocatalyst for hydrogen evolution. The resultant Ru-WO2.72 hybrid exhibits a superior Ru-based mass activity of 161.6 times higher than that of commercial Ru/C for hydrogen evolution, featuring a Tafel slope of 50 mV dec−1 and 40 mV overpotential at the current density of 10 mA cm−2. The uniform distribution of Ru species triggers a strong electron transfer across the Ru-WO2.72 Schottky barrier, resulting in a largely increased local electron density on the active Ru surface. Such electron enrichment induced by the Mott-Schottky effect at the metal-metal oxides interface is responsible for enhanced hydrogen production. This work demonstrates an effective strategy by Mott-Schottky effect to regulate electron distribution, which would evoke more inspiration in designing efficient electrocatalysis and beyond. 

Electron Redistribution of Ruthenium-Tungsten Oxides Mott-Schottky Heterojunction for Enhanced Hydrogen Evolution

With the progress in science and technology, non-oxide ceramics (NOCs) are playing a vital role in various fields at high temperature. However, under harsh service conditions, NOCs tend to be confr...

Progress in cognition of gas-solid interface reaction for non-oxide ceramics at high temperature

Carbon-based materials are commonly used supports for platinum (Pt) electrocatalysts in proton-exchange membrane (PEM) fuel cells. However, the limited stability of carbon supports poses a significant challenge in meeting the long lifespan of Pt catalysts. Carbon supports are prone to corrosion in fuel cells, resulting in detachment, aggregation, dissolution, and Ostwald ripening of supported Pt nanoparticles (NPs), leading to electrochemical surface area loss and decreased catalytic activity. In this review, we summarize recent progress in carbon-based catalyst supports and highlight the crucial role of modified carbon supports in oxygen reduction electrocatalysis. A comprehensive evaluation of several carbon support materials shows that support modification is critical for enhanced metal–support interaction and durability. Finally, the proposed perspectives highlight the key features of effective catalyst support for durable electrocatalysts in PEM fuel cells. 

Carbon-based catalyst supports for oxygen reduction in proton-exchange membrane fuel cells

Probing the Oxygen Reduction Reaction Intermediates and Dynamic Active Site Structures of Molecular and Pyrolyzed Fe–N–C Electrocatalysts by In Situ Raman Spectroscopy

Fe-N-C electrocatalysts have been demonstrated to be the most promising substitutes for benchmark Pt/C for oxygen reduction reaction (ORR). Herein, we report that, a N-doped carbon materials with trace amount of iron (0-0.08 wt.%) show excellent ORR activity and durability comparable and even superior to those of Pt/C in both alkaline and acidic media without the significant contribution by the metal sites. Such a N-doped carbon (denoted as N-HPCs) features a hollow and hierarchically porous architecture, and more importantly, a non-covalent-bonded N-deficient/N-rich heterostructure providing the active sites for oxygen adsorption and activation owing to the efficient electron transfer between the layers. The primary Zn-air battery using N-HPCs as the cathode delivers a much higher power density of 158 mW cm-2, and the maximum power density in H2-O2 fuel cell reaches 486 mW cm-2, which is comparable to and even better than those using conventional Fe-N-C catalysts at cathodes.

N-doped carbon electrocatalyst: marked ORR activity in acidic media without the contribution by metal sites?

With superior electrical and thermal properties, aluminum nitride (AlN) exhibits wide application. However, AlN is rather oxygen-sensitive and tends to be oxidized at high temperature. The surface ...

Wurtzite AlN(0001) Surface Oxidation: Hints from Ab Initio Calculations.

Siloxene features abundant functional groups and oxygen vacancies, which facilitates the ultrafine platinum nanoparticles loading for catalyzing hydrogen evolution reaction (HER). Herein, a siloxene-p-Pt-2 h composite has been fabricated with an ultralow platinum loading on siloxene (0.56 wt%), which shows greatly enhanced HER activity featuring an ultralow overpotential (η10 = 23 mV). Attractively, the siloxene-p-Pt-2 h has been applied as a HER catalyst in a Zn-H2O fuel cell, demonstrating a high power density of 157 mW cm−2 in coupling with the cathode hydrogen evolution. Moreover, a coupled configuration between two Zn-H2O fuel cells in series and the cell-powered hydroxide electrolyzer achieves the efficient hydrogen co-productions co-catalyzed by the HER catalysts. The excellent HER performance is attributed to the hydrophilic character and the optimal Gibbs free energy via the strong interaction between the siloxene and platinum nanoparticles. This work provides a novel design of self-powered co-productions of hydrogen. 

Pt NPs-loaded siloxene nanosheets for hydrogen co-evolutions from Zn-H2O fuel cells-powered water-splitting

The development of bifunctional electrocatalysts with efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is still a key challenge at the current stage. Herein, FeNi LDH/V2CTx/nickel foam (NF) self-supported bifunctional electrode was prepared via deposition of FeNi LDH on V2CTx/NF substrate by hydrothermal method. Strong interfacial interaction between V2CTx/NF and FeNi LDH effectively prevented the aggregation of FeNi LDH, thus exposing more catalytic active sites, which improved electrical conductivity of the nanohybrids and structural stability. The results indicated that the prepared FeNi LDH/V2CTx/NF required 222 mV and 151 mV overpotential for OER and HER in 1 M KOH to provide 10 mA cm−2, respectively. Besides, the FeNi LDH/V2CTx/NF electrocatalysts were applied to overall water splitting, which achieved a current density of 10 mA cm−2 at 1.74 V. This work provides ideas for improving the electrocatalytic performance of electrocatalysts through simple synthesis strategies, structural adjustment, use of conductive substrates and formation of hierarchical structures.

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Yafeng Chen

Papers

N-doped carbon electrocatalyst: marked ORR activity in acidic media without the contribution by metal sites?

Progress in cognition of gas-solid interface reaction for non-oxide ceramics at high temperature

Wurtzite AlN(0001) Surface Oxidation: Hints from Ab Initio Calculations.

Pt NPs-loaded siloxene nanosheets for hydrogen co-evolutions from Zn-H2O fuel cells-powered water-splitting

FeNi LDH/V2CTx/NF as Self-Supported Bifunctional Electrocatalyst for Highly Effective Overall Water Splitting