Ailing Pan,Xiaohui Sun,Yuanyuan Che,Yu Wang,Hong Du
COFs (covalent-organic frameworks) are regarded as ideal photocatalyst for hydrogen-evolution, due to their structural controllability, but they possess poor electrical conductivity and high exciton binding energy, which limits their photocatalytic activity. Here, the NiCo-ZIF-67 derived NiCo-nitrogen-doped carbon (NiCo-NC) with superior conductivity and high light-absorption capacity was spatially confined in the channels of TP-BD COF (TP: 2, 4, 6-triformylphloroglucino; BD: 4, 4′-biphenylenediamin) by constructing hydrogen bonds to form NiCo-NC@TP-BD COF core@shell heterojunctions and NiCo-NC acts as internal highly active nanoreactor, which could accelerate the photocatalytic efficiency. Specifically, the optimal catalyst [email protected] (NT-0.6) exhibits the maximum H 2 evolution rate of 78.97mmol g −1 h −1 without Pt cocatalyst, which is approximately 395 times higher than that of bare TP-BD COF. Systematic investigations imply that the NiCo-NC as a high active nanoreactor was stably encapsulated in the pore of TP-BD by hydrogen bonds and formed a close interfacial contact, which is revealed by Fourier-transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance ( 1 H NMR). Meanwhile, the charge transfer and Hydrogen Evolution Reaction (HER) are revealed by the density functional theory (DFT) calculation. This work offers a promising strategy to reduce the high excitation binding energy of COFs-based catalysts in photocatalytic H 2 evolution.
Kai Wu,Chenyang Chu,Qi Cao,Yijie Zheng,Jiajun Yu,Huiyan Zhang
NiCo@NC nanocatalysts were synthesized and employed for low-carbon alcohols. • The optimal reaction conditions of cellulose catalytic hydrogenolysis were systematically explored. • The ethanol yield (34.8 wt%) was achieved under the optimal reaction conditions. • The reaction route and mechanism of cellulose catalytic hydrogenolysis were analyzed. Sustainable Aviation Fuel (SAF), as an alternative to conventional fossil-based aviation fuels, has garnered widespread attention and considerable research, significantly reducing carbon emissions. Alcohols, as important oxygenated precursors, can be employed for the production of SAF. Here, the MOF nanocatalysts (NiCo@NC) were effectively synthesized and employed to catalyze cellulose into alcohols. The different catalysts and reaction conditions during catalytic hydrogenolysis of cellulose were systematically explored. The optimal reaction conditions for the NiCo@NC-catalyzed hydrogenolysis of cellulose to produce alcohols were identified, and the highest yield (34.8 wt%) of ethanol was obtained at a hydrogen pressure of 5 MPa, a reaction temperature of 210 °C, and a reaction time of 5 h, respectively, with 100% conversion of cellulose. The main formation pathway of alcohols was analyzed and explored. This work provides a potential conversion route for the production of alcohols. Download: Download high-res image (223KB) Download: Download full-size image
Urea is a common component present in both biological waste and water pollutants. Using it as an electrolyte substrate to replace the oxygen evolution reaction (OER) on the anode to assist hydrogen production is thermodynamically favorable and economically attractive. However, at high current densities (e.g., greater than 500 mA cm −2 ), the competitive adsorption of urea and OH − significantly limits the activity of the urea oxidation reaction (UOR). To overcome this challenge, this work designed and developed a catalyst consisting of a V-doped NiCo alloy, which is enclosed in an N-doped carbon layer. According to spectral characterization and density functional theory (DFT), the synergistic interaction between the N-doped carbon layer and V enhances the electron enrichment from the bulk to the surface. Meanwhile, the highly electronegative nitrogen atoms simultaneously regulate the local charge distribution of the carbon layer. This guarantees the optimal binding strength between reactants (urea and OH − ) and active sites. Consequently, V-NiCo@NC exhibits excellent urea oxidation performance ( E 10/1000 = 1.27/1.43 V RHE ). Additionally, the introduction of the N-doped carbon layer significantly improves the long-term durability of the catalyst, it can run steadily for 100 h at 1000 mA cm −2 . This work provides an approach for designing efficient UOR catalyst materials and offers insights for optimizing catalytic performance by balancing competing adsorption.
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