查看更多>>摘要：The piezo-photocatalytic effect of Au decorated bismuth oxybromide (BiOBr) was investigated to elucidate the regulation of built-in electric field on charge carrier dynamics and exploit the potential of multi-field coupled environmental purification. Physicochemical properties of Au-BiOBr such as the piezoelectricity, photoresponse characteristics, and charge separation efficiencies were thoroughly analyzed, meanwhile the degradation of carbamazepine (CBZ) was chosen to evaluate the catalytic performance of this system. The piezo-photocatalytic removal of CBZ reached 95.8% within 30 min, and the rate constant is 1.73 times higher than the sum of individual piezo- and photocatalytic ones. The results attribute to not only the modification of Au nanoparticles that accelerates charge transfer and improves light absorption, but also, more importantly, the piezoelectric effect of BiOBr that amplifies the built-in electric field and modulates the band structure alignment. This work demonstrates a promising environmental remediation strategy via the co-utilization of solar and mechanical energy in nature.
查看更多>>摘要：Herein, the ternary catalyst of reduced graphene oxide (rGO)-coated Ag/Cu2O-octahedron nanocrystals (Ag/Cu2O@rGO) was successfully fabricated by method of water bath combining with gas-bubbling-assisted membrane reduction. Supported Ag nanoparticles with low fermi energy can enrich the photogenerated electrons originated from visible light-driven Cu2O octahedral nanocrystals. The surface extended pi bond of coated rGO nanolayers on Ag/Cu2O can further capture photoelectrons and improve adsorption-activation capacities for reactants. Ag-n/Cu2O@rGO catalysts with ternary rGO-Ag-Cu2O heterojunction exhibit excellent performance during selective photocatalytic CO2 reduction with H2O into CH4. Ag-4/Cu2O@rGO catalyst has the highest formation rate (82.6 mu molg(-1) h(-1)) and selectivity (95.4%) of CH4 product. Combined with the results of in-situ DRIFT spectra and density functional theory calculations, the photocatalytic mechanism is proposed: the protonation of CO* intermediate is key step for selective photocatalytic CO2 reduction into CH4. It provides one novel strategy to development of high-efficient photocatalyst for selective CO2 conversion into C1 chemicals.
查看更多>>摘要：The electrochemical CO2 reduction to formic acid (HCOOH) by Bi-based catalysts has been considered an effective way to solve the energy and environmental crisis. However, achieving high selectivity, high current density, and long-term stability for HCOOH production, remains a substantial challenge. Herein, BiIn alloy nanoparticles (NPs), deriving from the bimetallic metal-organic frameworks, exhibit an excellent HCOOH Faradaic efficiency (FEHCOOH) of 92.5% at the current density of 300 mA cm(-2), as well as a production rate of 5170 mu mol h(-1) cm(-2). Moreover, the BiIn alloy NPs also achieve superior stability that over 25 h with less than 10% FE drop at the current density of 120 mA cm(-2) in a membrane electrode assembly system. In-situ spectra and theoretical calculations suggest that the Bi-In dual-metal sites can provide the optimal binding energy to *OCHO intermediate, thus accelerating the CO2 to HCOOH conversion.
查看更多>>摘要：Lanthanide-doped near-infrared (NIR) photocatalyst still obstructed by the less impressive photocatalytic efficiency and stability. In this work, we report a novel strategy by introducing the lanthanide-doped ferroelectric perovskites of SiTiO3 and Sr2Bi4Ti4O15 into the glass-ceramic (GC), then an efficient and stable NIR photocatalyst was fabricated through the method of facile in-situ HCl etching GC. The results show that Sr2Bi4Ti4O15, SrTiO3, and BiOCl were exposed to the superficial coating of the core-shell structured photocatalyst and constructed Zscheme heterojunction, the heterojunction with built-in electric field could significantly facilitate the charge carriers separation and harvest NIR light for photocatalytic reaction simultaneously. The evident increase of Lewis basic sites over defect-rich photocatalyst is found, the center dot O2- and center dot OH radicals are generated. During the degradation of norfloxacin (NOR) under NIR light irradiation for 90 min, the NOR degradation rate is 86% (TOC removal rate is 30.7%), the high apparent quantum yield of 2.3% is achieved.
查看更多>>摘要：Sodium p-perfluorous nonenoxybenzene sulfonate (OBS) as a novel alternative to perfluorooctane sulfonate (PFOS), belongs to the family of per- and polyfluoroalkyl substances (PFASs). We demonstrated that Co-based oligolayered MXene (Co@o-MXene) achieved the complete oxidation of OBS during catalytic ozonation with peroxymonosulfate (PMS). The optimized catalyst exhibited 78.5% OBS oxidation in only 2 min, and the oxidation route was thoroughly investigated by Fukui function calculations and QTOF-MS/MS analysis. However, within the fluoroprotein (FP) foam solution, high TOC removal was performed via the newly designed two-stage ozonation process. Systematic studies indicated that OBS can donate electrons through a Co center dot center dot center dot SO3 cation-pi bridge on the surface of o-MXene/PMS accompanied by the generation of reactive oxygen species (ROS), the strong adsorption energy (Eads) value of PMS, enhanced total density of states (TDOS) and uneven electron density in this reaction system. This work extended the potential of newly developed MXene family materials to decompose PFAS.
查看更多>>摘要：Carbon nitride (CN) with nitrogen vacancy is a robust photocatalyst with proven enhancing H2O2 production ability. However, nitrogen vacancy control is extremely challenging with the majority of reports representing it as a few vacancies. Herein, for the first time, the amorphous CN (ACN) with two N-2 C-site vacancies in one CN unit is prepared by a one-step H-2 plasma approach. First-principles calculations , experimental results provide consistent evidence that two N-2 C vacancies are located in one CN unit structure after amorphous transformation. Plasma-induced ACN is stable with a hierarchical continuous nanosheet network structure and exhibits an ul-trahigh specific surface area of ~405.76 m(2)g(-1), which is 83 times higher than that of pristine CN (4.89 m(2)g(-1)) and significantly enhanced photocatalytic H2O2 production, yielding 1874 mu molg(-1)h(-1). Besides, the existence potential drop of 2.61 eV for the electrostatic potential in ACN is key to charge carrier separation. Moreover, the amorphous transformation leads to a new strong band tail, which remarkably enhances the absorbance edge of ACN up to 593 nm, resulting in a wider range of visible-light absorption to enhance H2O2 production. The results have provided an effective approach for promoting the practical application of ACN in photocatalytic H2O2 production.
查看更多>>摘要：Facilely upgrading 5-Hydroxymethylfurfural (HMF) via controllable oxidation of aldehyde and hydroxymethyl groups has attracted increasing attention since one of the products, 2,5-Furandicarboxylic acid (FDCA), is of great industrial value. Herein, the surface reconstruction of NiFeP and underlying dynamic Ni(OH)2-NiOOH transformation are characterized under electro-anodic HMF oxidation reaction (HMFOR). The Ni(OH)2-NiOOH/ NiFeP heterojunction presents extraordinary HMFOR performance and produces FDCA with a yield over 99% and a Faradaic efficiency over 94%. The reconstructed NiOOH is suggested to chemically (not electrochemically) oxidize HMF while itself is reduced back to Ni(OH)2; The applied anodic potential then drives the oxidation of Ni (OH)2 to NiOOH, to circlize the HMF oxidation process. Meanwhile, the deeper oxidation of NiOOH to NiO(OH)2 or beyond can drive the oxygen evolution reaction (OER). Therefore, a NiOOH-centered dual-circle mechanism is unraveled to understand the entangled and competitive HMFOR and OER, which will be helpful to design better HMFOR electrocatalysts.
查看更多>>摘要：Hydrogenation of unsaturated biomass in a control manner is highly desirable but challenging, especially under mild conditions. We here report selective hydrogenation of alpha,beta-unsaturated aldehydes (UALs), featuring a precise control of all potential products by adjustment of the role of ammonia borane (AB) in transfer and/or catalytic hydrogenation. The hydrogenation can be readily operated in neat water without using any external H-2-source, because AB as the H-2-source is favorable in aqueous solution. Impressively, unsaturated alcohols are prepared in 100% conversion by the room-temperature transfer hydrogenation of UALs with AB, while saturated aldehydes are obtained in 100% conversion and > 90% selectivity with high activity (i.e., turnover frequency = 0.98 s(-1) for cinnamaldehyde), by the catalytic hydrogenation with H-2 released from AB and Pd immobilized on twodimensional metal organic layer. On the other hand, UALs can be completely converted into the saturated alcohols through a combination of transfer and catalytic hydrogenation in one pot. This strategy can be extended to more than 8 types of UALs, and provides a facile way to fine-control the selective hydrogenation of unsaturated compounds with competing bonds.
查看更多>>摘要：The photocatalytic peroxymonosulfate (PMS) activation process offers great potential for organic wastewater treatment. In this study, enol-incorporated carbon nitride (ECN) catalysts were used for PMS activation to degrade organic pollutants under visible-light irradiation. Our experimental and theoretical results revealed that the incorporation of enol into the poly-heptazine-based carbon nitride framework effectively tuned the electronic structure. The obtained ECN showed promoted PMS activation capability, along with increased visible-light harvesting ability and improved photogenerated charge separation. As a result, an excellent performance with a bisphenol A removal rate of 100% within 20 min and a total organic carbon (TOC) removal rate of 86% in 30 min was achieved in the Vis-PMS/ECN process. This was because ECN functioned as an efficient photocatalyst as well as PMS activator, which enabled the PMS activation process to proceed smoothly for center dot SO4- production under visible-light irradiation. These findings could offer some guidelines for the development of efficient metal-free photocatalysts in the persulfate-based advanced oxidation process for environmental remediation.
Sharma, RaghunandanGyergyek, SasoAndersen, Shuang Ma
12页
查看更多>>摘要：Determination of the electrochemical surface area (ECSA) of platinum supported on carbon (Pt/C) electro-catalysts through the hydrogen adsorption/desorption region has been revisited. Conventionally, ECSA is calculated by using the area of the H-adsorption (H-ad), H-desorption (H-de) or both of the regions to calculate the corresponding charge. Use of an appropriate baseline for the double-layer region is highly important for accurate determination of the associated charge. Unlike pure platinum, where a horizontal baseline for double-layer region is appropriate, the Pt/C catalysts have a skewed baseline for the double-layer region due to presence of surface functional groups from the support carbon. The skewness is not similar for the negative-going (cathodic) and the positive-going (anodic)scans, leading to significantly different H-ad and H-de charges. Again, the baselines from carbon may vary significantly during the catalyst durability study through an accelerated stress test (AST), due to oxidation of the support carbon. Present study investigates the effects of the baseline contribution on the ECSA calculations of Pt/C. It is observed that the baseline contribution for charge calculation (i) depends on the nature of the carbon support with significantly higher values (~10 fold) for H-de as compared to that for H-ad and (ii) increases for both the regions with the number of stress cycles during an AST. Hence, for Pt/C catalysts, while using a constant current baseline as a close approximation of the true baseline, charge associated to Had should be used for calculation of ECSA to access the catalyst activity as well as the durability in terms of %ECSA loss during AST.
NSTL
Elsevier