查看更多>>摘要：Electrocatalytic nitrate reduction reaction (NitRR) has gained attention because of its potential to mitigate environmental nitrogen pollution and recycle artificial nutrients. NitRR produces ammonia through complicated pathways that involve multistep electron transfer, while the formation of byproducts, e.g. toxic nitrite (NO2-), leads to lower energy efficiency and recontamination. In this work, we report the incorporation of CuOx active species into a TiO2-nanotube reactor (TiO2 NTs/CuOx) for the highly selective NitRR. In particular, the NO2- intermediate is diminished due to the hindered diffusion within the nanoconfined space. Thus, the CuOx modified nanoreactor performs a maximum faradaic efficiency of 92.23% and a yield rate of 1241.81 mu g h(-1) cm(-2) for nitrate-to-ammonia conversion. Theoretical insights further support a fundamental understanding of a cross scale interaction over the surface and interface. The findings suggest a promising approach for enhancing reaction activity and selectivity enabled by rationally designed active sites coupled with geometrically regulated structures.
查看更多>>摘要：Poisoning species, such as methanol and air pollutants, degrade the electrocatalytic activity for oxygen reduction reaction (ORR). Here, via taking advantage of the varied electronic property of nano-silicon, a versatile strategy is reported for enhancing the catalytic activity and anti-poisoning ability toward ORR by decorating noble metal catalysts with the size-controlled silicon nanoclusters (DS). Consequently, DS-Pd exhibits the enhanced ORR performance with a large halfwave potential of 0.892 V and an onset potential of 1.010 V. More importantly, it also shows enhanced anti-poisoning performance in methanol, NaNO2 and NaHSO3 electrolytes, compared to those of commercial Pt/C and Pd/C catalysts. Mechanism studies reveal that the synergistic effect between Pd and more oxygen-philic and less poison-philic Si nanoclusters largely abbreviate the absorption of poisoning species on the active sites. This strategy also improves the methanol-tolerant performance of Pt based catalysts, providing a versatile strategy for the fabrication of methanol-tolerant ORR catalysts.
查看更多>>摘要：The construction of S-scheme heterojunction catalysts is promising for efficient photocatalytic hydrogen production, but the conscious modulation of S-scheme charge transfer has remained largely underdeveloped. Herein, P and C modified Co2P/black TiO2 S-scheme heterojunction photocatalyst (Co2P/PC-b-TiO2) is prepared by pyrolyzing a mixture of cobalt phosphonate and TiO2 under H2 atmosphere. The in situ formed P and C dopants can not only enhance the ratio of surface active O species to bulk O defects but also inhibit anatase-to-rutile phase transformation, thereby ensuring the high intrinsic activity. More importantly, the S-scheme heterojunction between PC-b-TiO2 and Co2P is modified by the incorporation of P and C, wherein the intimately coupled heterointerface and strong internal electric field can accelerate charge separation and migration and optimize the available redox potential. Accordingly, Co2P/PC-b-TiO2 displays dramatically ascendant photocatalytic hydrogen evolution performance and outstanding stability. This study provides guidance for elaborately modifying Sscheme heterojunctions through heteroatom doping and heralds a new paradigm for engineering advanced heterojunction catalysts.
查看更多>>摘要：This study leverages piezocatalysis to accelerate redox reactions in heterogeneous peroxymonosulfate (PMS) activation. We syntheized few-layered molybdenum disulfide (MoS2) nanosheets as the piezoelectric catalyst for ultrasonic vibration (US)-coupled PMS system toward enhanced pollutant abatement. Scavenger tests, dissolved oxygen (DO) exclusion experiment and electron paramagnetic resonance (EPR) identify that sulfate radical (SO4.-) and singlet oxygen (O-1(2)) are the primary ROS in the US/MoS2/PMS system. Particularly, O-2(.-) is a vital intermediate for O-1(2) generation, and multiple formation pathways of O-1(2) were proposed in the US/MoS2/PMS system. With the assistance of DO and ultrasound, the utilization efficiency and activity of PMS will be remarkably increased because the majority of PMS evolves into more reactive SO4.- and O-1(2) for pollutant degradation. This work not only provides mechanistic insights into the interconnected regimes of piezocatalysis and heterogeneous Fenton-like reactions, but also achieves high chemical efficiency for sustainable water remediation.
查看更多>>摘要：This study develops an advanced single-atomic iron-loaded graphitic carbon nitride (Fe-1/CN) with unparalleled efficiency for converting peroxymonosulfate (PMS) to oxidants for water treatment. We found that acid-etching of Fe-1/CN leads to the reconstruction of conventional Fe-1-N-4 to Fe-1-C2N1 active sites. The acid-induced Fe-1-C2N1 sites are more favorable for PMS binding and have a lower energy barrier for O-1(2) production. The precise tuning of the coordination environment bestows the acid-etched Fe-1/CN with 29 times higher rate constants of bisphenol A degradation than its pristine counterparts. Further, the particulate catalysts were assembled into a self-supported catalytic membrane, which demonstrates excellent long-term durability throughout 170 h flow-through tests in both synthetic and real wastewater. This work provides pivotal insights into improving PMS activation activity by regulating the coordination environment around single atomic Fe sites. The engineering innovation laid the groundwork for new point-of-use water treatment devices.
Mendoza-Nunez, E. M.Solis-Garcia, A.Ortiz-Dominguez, C.Soto-Arteaga, C. E....
13页
查看更多>>摘要：This work reports the synthesis and catalytic application of binary Al2O3-Y2O3 (AlY-x) mixed oxides varying the Y2O3 wt% content (with x = 0 %, 25 %, 50 %, 75 %, and 100 %) prepared by hydrothermal treatment. For AlY-0, urchin-like structures composed of nanobelts and nanorods clearly showed the gamma-alumina phase. The AlY-25, AlY-50, and AlY-75 exhibited the formation of nanospheres and microspheres with homogeneous compositions. The surface analysis by XPS revealed the presence of carbonates in the yttrium content materials and a slight Al enrichment in the AlY-25 and AlY-50 samples. Our catalytic experiments demonstrate that changing the surface acid/base properties and tuning the yttria content can induce modifications in the structural and electronic properties, conduction character, morphology, and especially on the conversion and selectivity of 2-propanol transformation. The mechanism involved in the different pathways for the transformation of 2-propanol was revised under the light of FTIR in-situ reaction analysis, thermo-conductivity chromatography, and multidimensional gas chromatography.
查看更多>>摘要：Reasonable construction and engineering of optimal hierarchical photocatalysts have garnered great attention in terms of promoting CO2 photoreduction into fuel production. Herein, we introduce a novel 3D O-doped g-C3N4/N-doped Nb2O5 (OCNNb) S-scheme heterojunction fabricated using control of each material's surface charge-induced heteroaggregation for photocatalytic CO2 reduction (PCR). The optimized sample converts CO2 with substantially greater rates (the sum production rate of CO and CH4) than the blank control, i.e., O-doped g-C3N4 (OCN) and N-doped Nb2O5 (NNBO). The enhanced photocatalytic efficiency can not only be ascribed to the prevention of photogenerated charge carrier recombination mediated by the S-scheme heterojunction but also to the high specific surface areas and abundance of active sites. In the meantime, work function measurement, in situ irradiated, X-ray photoelectron spectroscopy and electron paramagnetic resonance (EPR) studies confirm the S-scheme photogenerated charge transfer mechanism. This study offers a useful approach for fabricating extremely effective heterojunction photocatalysts to convert solar fuels.
查看更多>>摘要：The interfacial electron modulation of electrocatalyst is an effective strategy to realize the oxidation of organic chemicals. Here, a heterojunction (CoP-CoOOH) is prepared via a modulating electron density between interfaces for 5-hydroxymethylfurfural (HMF) oxidation to 2,5-furanedioic acid (FDCA) in high concentration. Density Functional Theory (DFT) shows that heterojunction increased efficient charged active centers, enhanced the adsorption of the reactant on the surface of electrocatalyst, and improved the HMF oxidation reaction (HMFOR) activity. The electrolyzer using CoP-CoOOH as cathodic evolution H-2 and anodic HMFOR requires only voltage of 1.42 V. Additionally, the diffusion limitation of the reaction is overcome via coupling with the flow reactor, which further improved the HMFOR efficiency. Although the HMF concentration is 150 mM, the Faraday efficiency of HMF and the selectivity of FDCA in the flow reactor are 98.2 % and 99.4 %, respectively.
查看更多>>摘要：Here, we provide an in-depth understanding of the catalytic mechanism of sodium for the carburization of alpha-Fe catalyst by C2H4 in contrast to traditional CO through an approach combing in situ XRD and molecular orbital theory, considering the carburization of iron-based catalyst to active iron carbides is a prerequisite step to display activity in CO/CO2 hydrogenation. In situ XRD experiments show that sodium can trigger the carburization of alpha-Fe by CO and accelerate the accumulation of carbon-rich iron carbides, due to the enhanced electron back-donation from d band in Fe surface to 2 pi* orbitals in CO, thereby facilitating the dissociation of CO and the carburization by CO. Nevertheless, sodium shows a contrary effect on the carburization of alpha-Fe under C2H4, due to the significant increase of the total dissociative energy, thereby facilitating the desorption instead of dissociation of C2H4 on Fe surface, finally inhibiting the carburization.
查看更多>>摘要：The precise size-controlled formation of palladium (Pd) nanoclusters with size-dependent catalytic activity was achieved through a cage confinement strategy. In this process, three typical porous organic cages (POCs) with gradually decreasing cavity diameters were used as encapsulation carriers. A series of Pd nanoclusters-based catalysts with corresponding Pd cluster sizes of 0.73, 0.68, and 0.43 nm, respectively, was effectively fabricated by confining the Pd nanoclusters in size-adjustable cavities. The obtained Pd@POCs nanocatalysts exhibited excellent crystallinity, high stability, fascinating morphological characteristics, and superior catalytic hydrogenation performance. Especially, the size-dependent catalytic performance toward hydrogenation of 4nitrophenol and semi-hydrogenation of alkyne compounds was demonstrated by experimental results and theoretical calculations. The prepared Pd(1.71%)@FT-RCC3 catalyst with the smallest Pd cluster size of about 0.43 nm showed the best catalytic performance. This study promotes a better understanding of size-dependent catalysis and provides a new strategy for the fabrication of customized nanocatalysts.
NSTL
Elsevier