Hebei University of Technology

About: Hebei University of Technology is a education organization based out in Tianjin, China. It is known for research contribution in the topics: Catalysis & Microstructure. The organization has 17575 authors who have published 14584 publications receiving 129835 citations. The organization is also known as: Héběi Gōngyè Dàxué.

Self‐Supported Cobalt Phosphide Mesoporous Nanorod Arrays: A Flexible and Bifunctional Electrode for Highly Active Electrocatalytic Water Reduction and Oxidation

Abstract: Water splitting for the production of hydrogen and oxygen is an appealing solution to advance many sustainable and renewable energy conversion and storage systems, while the key fact depends on the innovative exploration regarding the design of efficient electrocatalysts. Reported herein is the growth of CoP mesoporous nanorod arrays on conductive Ni foam through an electrodeposition strategy. The resulting material of well-defined mesoporosity and a high specific surface area (148 m2 g−1) can be directly employed as a bifunctional and flexible working electrode for both hydrogen and oxygen evolution reactions, showing superior activities as compared with noble metal benchmarks and state-of-the-art transition-metal-based catalysts. This is intimately related to the unique nanorod array electrode configuration, leading to excellent electric interconnection and improved mass transport. A further step is taken toward an alkaline electrolyzer that can achieve a current density of 10 mA cm−2 at a voltage around 1.62 V over a long-term operation, better than the combination of Pt and IrO2. This development is suggested to be readily extended to obtain other electrocatalysis systems for scale-up water-splitting technology.

Ultrahard nanotwinned cubic boron nitride.

Abstract: The hardness, toughness and chemical stability of the well-known superhard material cubic boron nitride have been improved by using a synthesis technique based on specially prepared ‘onion-like’ precursor materials. Superhard polycrystalline cubic boron nitride, second only to diamond in hardness, is superior to diamond in terms of thermal and chemical stability and is used widely as an abrasive. The hardness of many materials can be improved by decreasing the grain size, and here Yongjun Tian and colleagues use this principle in a new synthesis technique — based on specially prepared 'onion-like' precursor materials — capable of increasing the hardness of cubic boron nitride. The structure of the resulting polycrystalline material is dominated by nanometre-scale twin domains, yielding a solid combining ultrahigh hardness (exceeding that of a synthetic diamond single crystal) with a high oxidization temperature and extreme fracture toughness. If nanotwins at similar scales can be reproduced in polycrystalline diamond, it may be possible to raise diamond itself to new levels of hardness and stability. Cubic boron nitride (cBN) is a well known superhard material that has a wide range of industrial applications. Nanostructuring of cBN is an effective way to improve its hardness by virtue of the Hall–Petch effect—the tendency for hardness to increase with decreasing grain size1,2. Polycrystalline cBN materials are often synthesized by using the martensitic transformation of a graphite-like BN precursor, in which high pressures and temperatures lead to puckering of the BN layers3. Such approaches have led to synthetic polycrystalline cBN having grain sizes as small as ∼14 nm (refs 1, 2, 4, 5). Here we report the formation of cBN with a nanostructure dominated by fine twin domains of average thickness ∼3.8 nm. This nanotwinned cBN was synthesized from specially prepared BN precursor nanoparticles possessing onion-like nested structures with intrinsically puckered BN layers and numerous stacking faults. The resulting nanotwinned cBN bulk samples are optically transparent with a striking combination of physical properties: an extremely high Vickers hardness (exceeding 100 GPa, the optimal hardness of synthetic diamond), a high oxidization temperature (∼1,294 °C) and a large fracture toughness (>12 MPa m1/2, well beyond the toughness of commercial cemented tungsten carbide, ∼10 MPa m1/2). We show that hardening of cBN is continuous with decreasing twin thickness down to the smallest sizes investigated, contrasting with the expected reverse Hall–Petch effect below a critical grain size or the twin thickness of ∼10–15 nm found in metals and alloys.

Mesoporous Phosphorus-Doped g-C3N4 Nanostructured Flowers with Superior Photocatalytic Hydrogen Evolution Performance

Abstract: Graphitic carbon nitride (g-C3N4) has been deemed a promising heterogeneous metal-free catalyst for a wide range of applications, such as solar energy utilization toward water splitting, and its photocatalytic performance is reasonably adjustable through tailoring its texture and its electronic and optical properties. Here phosphorus-doped graphitic carbon nitride nanostructured flowers of in-plane mesopores are synthesized by a co-condensation method in the absence of any templates. The interesting structures, together with the phosphorus doping, can promote light trapping, mass transfer, and charge separation, enabling it to perform as a more impressive catalyst than its pristine carbon nitride counterpart for catalytic hydrogen evolution under visible light irradiation. The catalyst has low cost, is environmentally friendly, and represents a potential candidate in photoelectrochemistry.

Identification and Regulation of Active Sites on Nanodiamonds: Establishing a Highly Efficient Catalytic System for Oxidation of Organic Contaminants

Abstract: Nanodiamonds exhibit great potential as green catalysts for remediation of organic contaminants. However, the specific active site and corresponding oxidative mechanism are unclear, which retard further developments of high-performance catalysts. Here, an annealing strategy is developed to accurately regulate the content of ketonic carbonyl groups on nanodiamonds; meanwhile other structural characteristics of nanodiamonds remain almost unchanged. The well-defined nanodiamonds with well-controlled ketonic carbonyl groups exhibit excellent catalytic activity in activation of peroxymonosulfate for oxidation of organic pollutants. Based on the semi-quantitative and quantitative correlations of ketonic carbonyl groups and the reaction rate constants, it is conclusively determined that ketonic carbonyl groups are the catalytically active sites. Different from conventional oxidative systems, reactive oxygen species in nanodiamonds@peroxymonosulfate system are revealed to be singlet oxygen with high selectivity, which can effectively oxidize and mineralize the target contaminants. Impressively, the singlet-oxygen-mediated oxidation system significantly outperforms the classical radicals-based oxidation system in remediation of actual wastewater. This work not only provides a valuable insight for the design of new nanocarbon catalysts with abundant active sites but also establishes a very promising catalytic oxidation system for the green remediation of actual contaminated water.