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Supramolecular electrostatic self-assembly of mesoporous thin-walled graphitic carbon nitride microtubes for highly efficient visible-light photocatalytic activities
摘要： For efficient solar energy conversion, the morphology engineering of hollow graphitic carbon nitride (g-C3N4) is one of the promising approachs benefiting from abundant exposed active sites and short photocarrier transport distances, but is difficult to control on account of easy structural collapse. Herein, a facile supramolecular electrostatic self-assembly strategy has been developed for the first time to fabricate mesoporous thin-walled g-C3N4 microtubes (mtw-CNT) with shell thickness of ca. 13 nm. The morphological control of g-C3N4 enhances specific surface area by 12 times, induces stronger optical absorption, widens bandgap by 0.18 eV, improves photocurrent density by 2.5 times, and prolongs lifetimes of charge carriers from bulk to surface, compared with those of bulk g-C3N4. As a consequence, the transformed g-C3N4 exhibits the optimum photocatalytic H2-production rate of 3.99 mmol·h?1·g?1 (λ > 420 nm) with remarkable apparent quantum efficiency of 8.7% (λ = 420 ± 15 nm) and long-term stability. Moreover, mtw-CNT also achieves high photocatalytic CO2-to-CO selectivity of 96% (λ > 420 nm), much better than those on the most previously reported porous g-C3N4 photocatalysts prepared by the conventional hard-templating and soft-templating methods.
关键词： Thin wall,Photocatalysis,Graphitic carbon nitride,H2 production,Mesoporous microtube,CO2 reduction
更新于2025-09-19 17:13:59
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Aluminium Matrix Composites Produced by Laser Based Additive Manufacturing
摘要： 3D laser metal deposition (LMD) based on the laser cladding is an established technique for additive manufacturing tasks. Also the laser cladding is a well-known technique to produce aluminum matrix composites reinforced by Si particles. High cooling rates typical for laser treatment enable to eliminate coarse Si particles formation which is a substantial disadvantage of in-situ Al-Si composites produced by traditional manufacturing processes like casting. The coarse Si particles formation reduces Al-Si composites mechanical properties. Extremely non-equilibrium solidification conditions typical for micro LMD process allow to obtain a further structure refinement and its mechanical properties improvement. In this paper the in-situ Al-Si composites produced by micro LMD process with different parameters sets were investigated by fine structure X-ray analysis. The structure and phase composition of in-situ Al-Si composites were described. The influence of cladding parameters on Al-Si composites structure was investigated.
关键词： MMC,aluminium matrix composites,Laser micro cladding,thin-wall parts,fine structure,additive manufacturing,aluminium alloys,X-ray analysis,thin wall
更新于2025-09-12 10:27:22