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Ni‐promoted electrocatalytic biomass reforming has shown promising prospect in enabling high value‐added product synthesis. Here, we developed a novel hybrid catalyst with Ni nanosheet forests anchored on carbon paper. The hybrid catalyst exhibits high efficiency in electrooxidation of HMF to FDCA coupling with H2 production in high purity. The Ni nanosheets have small crystal grain sizes with abundant edges, which is able to deliver an efficient HMF oxidation to FDCA (selectivity >99 %) at low potential of 1.36 VRHE with high stability. The post‐reaction structure analysis reveals the Ni nanosheets would transfer electrons to carbon and readily turn into NiOx and Ni(OH)x during the reaction. DFT results suggest high valence Ni species would facilitate the chemical adsorption (activation) of HMF revealing the reaction pathway. This work emphasizes the importance of the precise control of Ni activity via atomic structure engineering. [ABSTRACT FROM AUTHOR]

A new synthetic strategy was developed for the fabrication of polydopamine modified carbon nanotube catalysts via in situ polymerization and subsequent thermal treatment process. The hybrid nonmetallic catalysts exhibited superior apparent and intrinsic activity than undoped or nitrogen doped carbon nanotube materials in ethylbenzene dehydrogenation reactions. The relatively high catalytic activity could be attributed to the electron transfer from polydopamine to nanocarbon matrix. The immediate result is that the improved nucleophilicity enhanced the hydrogen abstraction activity of nanocarbon catalysts, which is recognized as the rate determining step in alkane dehydrogenation reactions. [ABSTRACT FROM AUTHOR]

N vacancy modified g-C 3 N 4 nano-fragments exhibit the improvement of photocatalytic performance for H 2 evolution due to synergistic effect of N vacancy and quantum confinement effect. • N vacancy modified g-C 3 N 4 nano-fragments were successfully prepared. • Quantum confinement effect was introduced in g-C 3 N 4 nano-fragments. • g-C 3 N 4 nano-fragments presented excellent photocatalytic activity. • The conduction band position of g-C 3 N 4 nano-fragments was easily adjusted. N vacancy modified g-C 3 N 4 nano-fragments were facilely prepared through thermal treatment method. The declined size and thickness of resultant g-C 3 N 4 nano-fragments make it possess quantum confinement effect. The synergistic effect of N vacancy and quantum confinement effect endows resulting g-C 3 N 4 nano-fragments with bigger surface area, stronger light response ability and improved migration effect of photoinduced charge. Not only that, the existence of quantum confinement effect remedies the shortcoming that reduced intrinsic conduction band potential was caused by N vacancy, and the conduction band position was easily adjusted. When N vacancy modified g-C 3 N 4 nano-fragments were used to produce H 2 , the H 2 evolution rate of the best sample (nano-CN5) was 5.9 folds more than bulk g-C 3 N 4 and kept admirable stability of performance, structure and feature. Clearly, the present work develops a useful strategy for adjusting conduction band position of g-C 3 N 4 and a meaningful thought for changing band gap of other photocatalysts. [ABSTRACT FROM AUTHOR]

Borocarbonitrides (BCNs) have emerged as highly selective catalysts for the oxidative dehydrogenation (ODH) reaction. However, there is a lack of in-depth understanding of the catalytic mechanism over BCN catalysts due to the complexity of the surface oxygen functional groups. Here, BCN nanotubes with multiple active sites are synthesized for oxygen-assisted methanol conversion reaction. The catalyst shows a notable activity improvement for methanol conversion (29%) with excellent selectivity to formaldehyde (54%). Kinetic measurements indicate that carboxylic acid groups on BCN are responsible for the formation of dimethyl ether, while the redox catalysis to formaldehyde occurs on both ketonic carbonyl and boron hydroxyl (B─OH) sites. The ODH reaction pathway on the B─OH site is further revealed by in situ infrared, x-ray absorption spectra, and density functional theory. The present work provides physical-chemical insights into the functional mechanism of BCN catalysts, paving the way for further development of the underexplored nonmetallic catalytic systems., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Sustainable and environmentally benign catalytic processes are vital for the future to supply the world population with clean energy and industrial products. The replacement of conventional metal or metal oxide catalysts with earth abundant and renewable nonmetallic materials has attracted considerable research interests in the field of catalysis and material science. The stable and efficient catalytic performance of nanocarbon materials was discovered at the end of last century, and these materials are considered as potential alternatives for conventional metal-based catalysts. With its rapid development in the past 20 years, the research field of carbon catalysis has been experiencing a smooth transition from the discovery of novel nanocarbon materials or related new reaction systems to the atomistic-level mechanistic understanding on the catalytic process and the subsequent rational design of the practical catalytic reaction systems. In this Account, we summarize the recent progress in the kinetic and mechanistic studies on nanocarbon catalyzed alkane oxidative dehydrogenation (ODH) reactions. The paper attempts to extract general concepts and basic regularities for carbon catalytic process directing us on the way for rational design of novel efficient metal-free catalysts. The nature of the active sites for ODH reactions has been revealed through microcalorimetric analysis, ambient pressure X-ray photoelectron spectroscopy (XPS) measurement, and in situ chemical titration strategies. The detailed kinetic analysis and in situ catalyst structure characterization suggests that carbon catalyzed ODH reactions involve the redox cycles of the ketonic carbonyl-hydroxyl pairs, and the key physicochemical parameters (activation energy, reaction order, and rate/equilibrium constants, etc.) of the carbon catalytic systems are proposed and compared with conventional transition metal oxide catalysts. The proposal of the intrinsic catalytic activity (TOF) provides the possibility for the fair comparisons of different nanocarbon catalysts and the consequent structure-function relation regularity. Surface modification and heteroatom doping are proved as the most effective strategies to adjust the catalytic property (activity and product selectivity etc.) of the nanocarbon catalysts. Nanocarbon is actually a proper candidate platform helping us to understand the classical catalytic reaction mechanism better, since there is no lattice oxygen and all the catalytic process happens on nanocarbon surface. This Account also exhibits the importance of the in situ structural characterizations for heterogeneous nanocarbon catalysis. The research strategy and methods proposed for carbon catalysts may also shed light on other complicated catalytic systems or fields concerning the applications of nonmetallic materials, such as energy storage and environment protection etc.