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Hybrid nanomaterials with controlled dimensions, intriguing components and ordered structures have attracted significant attention in nanoscience and technology. Herein, we report a facile and green polyoxometallate (POM)‐assisted hydrothermal carbonization strategy for synthesis of carbonaceous hybrid nanomaterials with molecularly dispersed POMs and ordered mesopores. By using various polyoxometallates such as ammonium phosphomolybdate, silicotungstic acid, and phosphotungstic acid, our approach can be generalized to synthesize ordered mesoporous hybrid nanostructures with diverse compositions and morphologies (nanosheet‐assembled hierarchical architectures, nanospheres, and nanorods). Moreover, the ordered mesoporous nanosheet‐assembled hierarchical hybrids with molecularly dispersed POMs exhibit remarkable catalytic activity toward the dehydration of tert‐butanol with the high isobutene selectivity (100 %) and long‐term catalytic durability (80 h). [ABSTRACT FROM AUTHOR]

Abstract: The realization of asymmetric hollow carbonaceous nanostructures remains a great challenge, especially when biomass is chosen as the carbon resource through hydrothermal carbonization (HTC). Herein, a simple and straightforward solvent‐induced buckling strategy is demonstrated for the synthesis of asymmetric spherical and bowl‐like carbonaceous nanomaterials. The formation of the bowl‐like morphology was attributed to the buckling of the spherical shells induced by the dissolution of the oligomers. The bowl‐like particles prepared through this solvent‐driven approach demonstrated a well‐controlled morphology and a uniform particle size of approximately 360 nm. The obtained nanospheres and nanobowls were loaded with CoS2 nanoparticles to act as heterogeneous catalysts for the selective hydrogenation of aromatic nitro compounds. As expected, the CoS2/nanobowls catalyst showed good tolerance to a wide scope of reducible groups and afforded both high activity and selectivity in almost all the tested substrates. [ABSTRACT FROM AUTHOR]

The tedious and costly route of the general nanocasting method hinders the commercial application of mesoporous non-precious metal catalysts based on transition metal-coordinating nitrogen-doped carbons (MN/C). Here, a simple, economic and sustainable hydrothermal carbonization (HTC)/soft templating method is demonstrated for the direct preparation of mesoporous FeN/C materials (FeN/MC). By this method, FeN/MC materials with high specific surface area, hierarchically mesoporous structure, and appropriate iron and nitrogen contents are prepared. The optimized FeN/MC materials exhibit superior catalytic performance in the oxygen reduction reaction (ORR) to commercial Pt/C in 0.1 M KOH. This confirms that the materials are one of the most efficient non-precious metal catalysts for the ORR in alkaline electrolyte. In addition, considerable durability and ORR activity are demonstrated by the FeN/MC materials in 0.1 M HClO4. Thus, this HTC/soft templating method has great promise for the practical application of this kind of non-precious metal catalysts in the ORR. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) of carbohydrates in general has been reported as a sustainable and green technique to produce novel carbon materials. Traditional HTC of carbohydrates leads to irregular carbonaceous particles with low porosity due to inevitable aggregation induced by the high surface energy and the failure of classical templates. The accrescent understanding of the reaction mechanism in the HTC "dark box" provides possibilities of engineering HTC carbonaceous materials in a refined way. In the past decades, some unprecedented carbonaceous structures were achieved via modified HTC processes. Those progresses reflect the mightiness of HTC for precise synthesis however the last specialized review on this topic is over a decade old. In this review, we summarize the advances in the precise engineering of carbonaceous materials with specific morphologies and structures by the bottom-up HTC of carbohydrates, especially monosaccharides and disaccharides. This review elucidates the HTC set screws for the shaping of and/or the pore-creation within the targeted nanostructured carbonaceous materials. The benefits for applications arised from the special control of HTC carbon are also discussed. This review could inspire further insight into the HTC process and broader application of carbon nanostructures made from renewable resources. [ABSTRACT FROM AUTHOR]