Dialkyl carbonates are important organic compounds and chemical intermediates with the label of "green chemicals" due to their moderate toxicity, biodegradability for human health and environment. Indeed, owing to their unique physicochemical properties and versatility as reagents, a variety of phosgene-free processes derived from CO or CO2 have been explored for the synthesis of dialkyl carbonates. In this critical review, we highlight the recent achievements (since 1997) in the synthesis of dialkyl carbonates based on CO and CO2 utilization, particularly focusing on the catalyst design and fabrication, structure-function relationship, catalytic mechanisms and process intensification. We also provide an overview regarding the applications of dialkyl carbonates as fuel additives, solvents and reaction intermediates (i.e. alkylating and carbonylating agents). Additionally, this review puts forward the substantial challenges and opportunities for future research associated with dialkyl carbonates.

Conversion of light alkanes into industrial chemical olefins via oxidative dehydrogenation (ODH) is a promising route because of favorable thermodynamic and kinetic characteristics, but encounters difficulties in selectivity control for olefins because of over-oxidation reactions that produce a substantial amount of undesired carbon oxides. Compared to widely-developed metal oxide-based catalysts, functionalized boron nitride has recently been shown as a competitive system in the ODH of light alkanes because of its more superior selectivity toward olefins as well as negligible formation of CO2. It is also characterized by high productivity to light olefins, remarkable catalyst stability, superior anti-oxidation ability, and excellent thermal conductivity. This feature article highlights the recent developments in applying boron nitride towards the ODH reaction of light alkanes. By correlating structural character with catalytic behavior, we expect to provide more insights into the catalytic nature of boron nitride-based materials in ODH reactions. Finally, we envisage perspective directions for boron-based ODH catalysts.

Metal-free boron- and carbon-based catalysts for the oxidative dehydrogenation of light alkanes is reviewed from the preparation methods, characterization, catalytic performance and mechanistic issues.

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Hexagonal boron nitride (h-BN) has lately received great attention in the oxidative dehydrogenation (ODH) reaction of propane to propylene for its extraordinary olefin selectivity in contrast to metal oxides. However, high crystallinity of commercial h-BN and elusive cognition of active sites hindered the enhancement of utilization efficiency. Herein, four kinds of plasmas (N 2 , O 2 , H 2 , Ar) were accordingly employed to regulate the local chemical environment of h-BN. N 2 -treated BN exhibited a remarkable activity, i.e., 26.0 % propane conversion with 89.4 % selectivity toward olefins at 520 8C. Spectroscopy demonstrated that "three-boron center" N-defects in the catalyst played a pivotal role in facilitating the conversion of propane. While the sintering effect of the "BO x " species in O 2 -treated BN, led to the suppressed catalytic performance (12.4 % conversion at 520 8C).

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HIGHLIGHTS• The crystal facets featured with facet-dependent physical and chemicalproperties can exhibit varied electrocatalytic activity toward hydrogen evolutionreaction (HER) and oxygen evolution reaction (OER) attributed to theiranisotropy.• The highly active exposed crystal facets enable increased mass activity of activesites, lower reaction energy barriers, and enhanced catalytic reaction rates forHER and OER.• The formation mechanism and control strategy of the crystal facet, significantcontributions as well as challenges and perspectives of facet-engineered catalystsfor HER and OER are provided.