RESUMO
Enabling high-efficiency solar thermal conversion (STC) at catalytic active site is critical but challenging for harnessing solar energy to boost catalytic reactions. Herein, we report the direct integration of full-spectrum STC and high electrocatalytic oxygen evolution activity by fabricating a hierarchical nanocage architecture composed of graphene-encapsulated CoNi nanoparticle. This catalyst exhibits a near-complete 98% absorptivity of solar spectrum and a high STC efficiency of 97%, which is superior than previous solar thermal catalytic materials. It delivers a remarkable potential decrease of over 240 mV at various current densities for electrocatalytic oxygen evolution under solar illumination, which is practically unachievable via traditionally heating the system. The high-efficiency STC is enabled by a synergy between the regulated electronic structure of graphene via CoNi-carbon interaction and the multiple absorption of lights by the light-trapping nanocage. Theoretical calculations suggest that high temperature-induced vibrational free energy gain promotes the potential-limiting O* to OOH* step, which decreases the overpotential for oxygen evolution.
RESUMO
The industrial production of nylon 6 usually includes synthesizing caprolactam through the cyclohexanone-hydroxylamine route. This approach requires complex protocols, elevated temperatures, noble metal catalysts and the use of hazardous strong acids or hydroxylamine. Additionally, a significant quantity of ammonium sulphate is generated during the synthesis procedure. This study aims to develop an electrochemical reduction system for the conversion of ADN generated from the electrolytic dimerization of acrylonitrile (AN) to 6-aminocapronitrile (ACN), a precursor of nylon 6. This system utilizes a cost-effective Cu nanomaterial under eco-friendly conditions, avoiding lengthy and harsh processes, eliminating NH2OH use, and reducing low-value ammonium sulfate generation. This electrosynthesis method maintains approximately 85% ACN selectivity at 40-100 mA cm-2 when passing the charge required for 37% theoretical conversion. When extending the reaction time to achieve an 80% conversion, ACN selectivity still reached 81.6%, exceeding the theoretical value of non-selective hydrogenation by 20%. The pseudo-first-order reaction kinetic modeling proves that the reaction rate constant for ADN hydrogenation is significantly greater than that for ACN hydrogenation, highlighting the selectivity advantage of the system for ACN. This study establishes the foundation for developing a continuous electrolysis process to produce the nylon 6 precursor from AN feedstock.
RESUMO
Achieving CO oxidation at room temperature is significant for gas purification but still challenging nowadays. Pt promoted by 3d transition metals (TMs) is a promising candidate for this reaction, but TMs are prone to be deeply oxidized in an oxygen-rich atmosphere, leading to low activity. Herein we report a unique structure design of graphene-isolated Pt from CoNi nanoparticles (PtÇCoNi) for efficiently catalytic CO oxidation in an oxygen-rich atmosphere. CoNi alloy is protected by ultrathin graphene shell from oxidation and therefore modulates the electronic property of Pt-graphene interface via electron penetration effect. This catalyst can achieve near 100% CO conversion at room temperature, while there are limited conversions over Pt/C and Pt/CoNiOx catalysts. Experiments and theoretical calculations indicate that CO will saturate Pt sites, but O2 can adsorb at the Pt-graphene interface without competing with CO, which facilitate the O2 activation and the subsequent surface reaction. This graphene-isolated system is distinct from the classical metal-metal oxide interface for catalysis, and it provides a new thought for the design of heterogeneous catalysts.
RESUMO
Decoupled electrolysis of water is a promising strategy for peak load regulation of electricity. The key to developing this technology is to construct decoupled devices containing stable redox mediators and corresponding efficient catalysts, which remains a considerable challenge. Herein, we designed a high-performance device, using polysulfides as mediators and graphene-encapsulated CoNi as catalysts. It produced H2 with a low potential of 0.82 V at 100 mA/cm2, saving 60.2% more energy than direct water electrolysis. The capacity of H2 production reached 2.5×105 mAh/cm2, which is the highest capacity reported so far. This device exhibited excellent cyclability in 15-day recycle tests, without any decay of performance. The calculation results revealed that the electronic structure of the graphene shell was modulated by the electron transfer from N-dopant and metal core, which significantly facilitated recycle of polysulfides on graphene surfaces. This study provides a promising method for constructing a smart grid by developing efficient decoupled devices.
RESUMO
Fully inactivating SARS-CoV-2, the virus causing coronavirus disease 2019, is of key importance for interrupting virus transmission but is currently performed by using biologically or environmentally hazardous disinfectants. Herein, we report an eco-friendly and efficient electrochemical strategy for inactivating the SARS-CoV-2 using in-situ formed nickel oxide hydroxide as anode catalyst and sodium carbonate as electrolyte. At a voltage of 5 V, the SARS-CoV-2 viruses can be rapidly inactivated with disinfection efficiency reaching 95% in only 30 s and 99.99% in 5 min. Mass spectrometry analysis and theoretical calculations indicate that the reactive oxygen species generated on the anode can oxidize the peptide chains and induce cleavage of the peptide backbone of the receptor binding domain of the SARS-CoV-2 spike glycoprotein, and thereby disables the virus. This strategy provides a sustainable and highly efficient approach for the disinfection of the SARS-CoV-2 viruliferous aerosols and wastewater.
RESUMO
The lack of highly efficient, inexpensive catalysts severely hinders large-scale application of electrochemical hydrogen evolution reaction (HER) for producing hydrogen. MoS2 as a low-cost candidate suffers from low catalytic performance. Herein, taking advantage of its tri-layer structure, we report a MoS2 nanofoam catalyst co-confining selenium in surface and cobalt in inner layer, exhibiting an ultra-high large-current-density HER activity surpassing all previously reported heteroatom-doped MoS2. At a large current density of 1000 mA cm-2, a much lower overpotential of 382 mV than that of 671 mV over commercial Pt/C catalyst is achieved and stably maintained for 360 hours without decay. First-principles calculations demonstrate that inner layer-confined cobalt atoms stimulate neighbouring sulfur atoms while surface-confined selenium atoms stabilize the structure, which cooperatively enable the massive generation of both in-plane and edge active sites with optimized hydrogen adsorption activity. This strategy provides a viable route for developing MoS2-based catalysts for industrial HER applications.
RESUMO
Despite tremendous importance in catalysis, the design of oxide-metal interface has been hampered by the limited understanding of the nature of interfacial sites and the oxide-metal interaction (OMI). Through construction of well-defined Cu2O/Pt, Cu2O/Ag and Cu2O/Au interfaces, we find that Cu2O nanostructures (NSs) on Pt exhibit much lower thermal stability than on Ag and Au, although they show the same structure. The activities of these interfaces are compared for CO oxidation and follow the order of Cu2O/Pt > Cu2O/Au > Cu2O/Ag. OMI is found to determine the activity and stability of supported Cu2O NSs, which could be described by the formation energy of interfacial oxygen vacancy. Further, electronic interaction between Cu+ and metal substrates is found center to OMI, where the d band center could be used as a key descriptor. Our study provides insight for OMI and for the development of Cu-based catalysts for low temperature oxidation reactions.
RESUMO
Perturbing the electronic structure of the MoS2 basal plane by confining heteroatoms offers the opportunity to trigger in-plane activity for the hydrogen evolution reaction (HER). The key challenge consists of inducing the optimum HER activity by controlling the type and distribution of confined atoms. A distance synergy of MoS2 -confined single-atom rhodium is presented, leading to an ultra-high HER activity at the in-plane S sites adjacent to the rhodium. By optimizing the distance between the confined Rh atoms, an ultra-low overpotential of 67â mV is achieved at a current density of 10â mA cm-2 in acidic solution. Experiments and first-principles calculations demonstrate a unique distance synergy between the confined rhodium atoms in tuning the reactivity of neighboring in-plane S atoms, which presents a volcanic trend with the inter-rhodium distance. This study provides a new strategy to tailor the activity of MoS2 surface via modulating the distance between confined single atoms.