查看更多>>摘要：This research provides a innovatively designed mechanism of activating the passivation layer on Fe~0 surface as semiconductor to construct a Z-scheme heterojunction in-situ for high-efficiency environmental remediation. Aggregation and passivation of Fe~0 and poor visible-light absorption of TiO2 were simultaneously improved by the facile synthesis of a recyclable Fe~0@black-TiO2 Z-scheme heterojunction without high-temperature hydrogen atmosphere. The results showed that tetracycline (TC) degradation efficiency with Fe~0@black-TiO2 was 1.23 and 2.63 times higher than that of pristine Fe~0 and black-TiO2, respectively. The superior degradation arose from strong reduction ability of highly dispersed Fe~0 and in-situ constructed Z-scheme heterojunctions. High dispersion of Fe~0, construction of the heterojunction, enhanced photodegradability of Fe~0@black-TiO2 were systematically elucidated by multiple characterization techniques. Furthermore, photodegradation pathways of TC based on the role of ·O2~- and ·OH were identified. Our results have provided the necessary inspiration and guidance for the development and application prospect of Fe~0@black-TiO2 in environmental remediation.
查看更多>>摘要：Herein, Fe-g-C3N4/Bi2WO6 Z-scheme heterojunction is elaborately designed to build a photo-Fenton system for the degradation of tetracycline (TC). In this study, the H2O2 decomposition performance of the Z-scheme heterojunction has been improved due to the doping of iron, improve photogenerated electrons transportability and facilitate spread of radicals, according to the efficacy analyses, and trapping experiment, ESR analysis as well as degradation pathways of TC. Moreover, DFT theoretical results suggest that the Z-scheme transfer route coupled with the generated photo-Fenton process builds a Z-scheme-charge-transfer platform for remarkable degradation of emerging pollutants, and the formation of Fe-N4 sites induces a spin polarization of the material and also introduces a defect state in the original forbidden band, which leads to extremely activity for the removal of TC in the photo-Fenton system. The study shows that ~1O2 and ·O_(2-) are the main active species participating in the degradation process.
查看更多>>摘要：In this study, bio-inspired single-atom Fe (bio-SA-Fe) sites with pyrrole-type FeN4 coordinations were embedded in graphitic carbon nitride (g-C3N4) via facile copolymerization approach. The bio-SA-Fe/g-C3N4 outperforms pure g-C3N4 and Fe-doped g-C3N4 (pyridine-type FeN4 sites) in photo-Fenton-like reaction with a broad operating pH range (3-9), low consumption of H2O2, and remarkable stability and durability. Bader charge and differential charge distribution reveals the pyrrole-type FeN4 sites are more conducive to charge distribution than the pyridine-type FeN4 sites in g-C3N4, enabling faster electron transfer between the conjugated bio-SA-Fe sites and the g-C3N4 substrate. Density functional theory calculations further verified that the bio-SA-Fe sites are more stable and possess higher intrinsic activity for heterogeneous Fenton reaction than the pyridine-type FeN4 sites in g-C3N4. This work provides important guidance for the rational design of robust bio-inspired single-atom catalysts for environmetal remediation and wide implications for other aqueous redox reactions.
查看更多>>摘要：This paper reports on the ethyl acetate (EA) removal over a honeycomb catalyst using an experimental design methodology. A mathematical model based on the response surface methodology is developed to evaluate the effect of parameters such as specific input energy (SIE), humidity, and EA concentration on the response variables (i.e., removal and energy efficiency). A set of experiments based on a statistical three-level full-factorial design of the experimental method were performed to collect the removal data. The model (R1~2 = 0.9858 and R2~2 = 0.9305 for removal and energy efficiency, respectively) indicates a satisfactory correlation between the experimental and predicted values. The analysis results using the model show that SIE is the principal parameter affecting the EA removal. Besides, verification of the experimental results indicates that the EA removal of 90.93% and the energy efficiency of 2.91 g.kWh~(-1) at 235 J L~(-1), 1.5%, and 30.3 ppm were achieved under optimal conditions.
查看更多>>摘要：The efficiency of photocatalytic molecular oxygen (O2) activation is limited by the poor O2 adsorption and the obstruction of electron transfer. Herein, we designed a graphite carbon nitride with surface B-N bond (Bx-C3N4) to improve its efficiency. A series of characterizations and DFT calculations show that boron atom replaces carbon atom to form B-N bond, which increase the O2 adsorption energy from - 0.47 eV to - 1.17 eV. Moreover, the doped boron atom can be used as the electron capture center to transfer electrons to the N atom, then to the surface adsorbed O2 through the N-O bond, thus improving the photocatalytic generation of ·O2~- and ~1O2. Finally, the photocatalytic degradation rates of RhB, tetracycline and o-nitrophenol by B0.05-C3N4 are 12.3, 4.8 and 18.5 times that of pure g-C3N4, respectively. Moreover, the degradation pathway and toxicity prediction of intermediates of RhB are proposed based on the results of HPLC-MS and DFT calculations.
查看更多>>摘要：The application of promising persulfate-based advanced oxidation processes (AOPs) for environment remediation is limited by the poor charge separation and the sluggish kinetic for active centers regeneration of the catalysts. Piezocatalytic activation has been proposed to solve the above concern recently, but little is known on its mechanism. Herein, novel piezocatalyst Bi2Fe4O9 nanosheets (BFO NSs) are demonstrated to significantly improve peroxydisulfate (PDS) activation efficiency via piezocatalysis, resulting SO4~(·-) and ·OH as the dominant active species for organic pollutants degradation. Further DFT calculations and experimental investigations confirm that the Fe~(2+) in BFO NSs as active sites donate electrons for PDS to generate SO4~(·-), and simultaneously that the piezo-electrons can accelerate the regeneration of Fe~(2+), thus leading to the superior catalytic activity. This work provides atomic-scale insights of catalytic sites and mechanisms of piezocatalytic PDS activation and may inspire the development of more efficient piezocatalysts and AOPs.
查看更多>>摘要：It is important yet difficult to distinguish the specific roles of superficial Ox~(n-) and interfacial lattice oxygen in catalytic combustion, especially over catalysts consisting of reducible metal oxides. In this study, based on the comparison of two natural counterparts with similar structure - CeO2 (an Ox~(n-) generator) and Pr6O_(11) (a lattice oxygen contributor), it is suggested that the catalytic combustion of propane under lean-burn conditions followed a typical Mars-van Krevelen mechanism, in which catalyst lattice oxygen represented the dominant reactive phases while superficial Ox~(n-) played negligible roles. As for soot combustion, adsorbed Ox~(n-) represented more sustainable oxidants than lattice oxygen (drained easily at the beginning of the reactions). Such a comparison is readily achieved and widely applicable, which may shed light on the identification of dominant reactive phases for various oxidation reactions over oxide-based catalysts.
查看更多>>摘要：Water electrolysis has been recognized as one of the most promising approaches to produce green hydrogen and eventually target carbon neutrality. Various cost-effective and light transition metal sulfides have been developed as the electrocatalysts to promote hydrogen evolution reaction (HER), one half-reaction of water electrolysis. Unfortunately, full use of their intrinsic electrocatalytic traits and exposed active sites is still challenging. Here, a nonstoichiometric titanium sulfide/nickel sulfide (TiS_(2-x)/NiS) hetero-catalyst is designed and constructed to induce a high-density of sulfur vacancies. As a HER electrocatalyst, it features the overpotentials of only 63 and 134 mV at a current density of 10 mA cm~(-2) in 1.0 M KOH and 0.5 M H2SO4, respectively, which is equipped with glorious durability even at high current densities (e.g., 100 mA cm~(-2) and 500 mA cm~(-2)). Such outstanding performance partially stems from the sulfur vacancies induced by a nonstoichiometric effect, namely the intensified interfacial charge transfer nearby the TiS_(2-x)/NiS heterointerface. The existence of sulfur vacancies partially regulates the d-electronic structure of Ti and Ni active sites, ultimately bringing in reduced energy barrier of water dissociation as well as optimized adsorption free energy for H* intermediates. The strategy of employing both a nonstoichiometric effect and interface engineering of a metal sulfide catalyst paves a new way to design high-performance and cost-effective HER electrocatalyst in universal media.
查看更多>>摘要：An In-doped Mo2C (In@Mo2C-d) is described as a photocatalyst for efficient and selective CO2 reduction. It is prepared by a metal organic framework (MOF)-engaged approach combining ion exchange and carbothermal reduction and illustrates a self-core-shell nanoflower structure with rich defects. The photocatalyst performs visible light-driven CO2-to-CO reduction with 97.3% selectivity at 234.4 μmol g~(-1) h~(-1) in aqueous media. Physicochemical measurements - isotopic labelling, time-resolved photoluminescence, in situ FT-IR, density functional theory - have been used to probe the photocatalytic mechanism. The combined analyses show that electrons are localized at neighboring Mo sites with localized defects and the d-band center is closer to the Fermi level after In doping, beneficial for the photocatalysis. They also suggest that In@Mo2C-d can stabilize COOH* intermediates and facilitate CO* desorption. The results point to a previously unreported CO2 reduction photocatalyst based on molybdenum carbide in which reactivity is promoted by doping and defect engineering.
查看更多>>摘要：Aiming for purification the trace amount of CO in H2-rich streams with reduced energy consumption and low cost, solar-driven photothermal preferential oxidation of carbon monoxide on the non-precious metal oxide catalyst is proposed in this work. Cu doped CuCeO_(2-x) nanorods catalysts were synthesized with a fast and simple coprecipitation method at the room temperature, which shows high CO oxidation activity in photothermal preferential oxidation of CO (CO-PROX) under UV-Vis-IR light irradiation. Rely on the various characterization methods such as UV-Vis-IR diffuse reflection spectrum (UV-Vis-IR DRS), photoluminescence spectrum (PL), transient photocurrent test, HRTEM, XRD, XPS, UV-Raman and H2-TPR, the optical and chemical properties of the CuCeO_(2-x) nanorods catalysts were uncovered. The photothermal catalytic activity of CuCeO_(2-x) nanorods doped with 10 wt% Cu reaches to 90% CO conversion under Xe lamp illumination (2.5 suns), and the solar driven photothermal CO-PROX reaction on CuCeO_(2-x) nanorods were proposed to be proceeded by the light-to-thermal conversion and subsequently to drive a thermal catalytic process. The catalytic performance of CuCeO_(2-x) nanorods in photothermal CO-PROX is closely related to the photo-to-thermal conversion efficiency and Cu-Ce synergetic interaction of CuCeO_(2-x) nanorods catalyst. The introduction of CuOx greatly broaden the optical absorption range and promotes the light absorption capacity of ceria nanorods, which induces the catalyst with high photo-to-thermal conversion capability. Moreover, the optimal copper dopant benefits to enhance the Cu-Ce synergetic interaction and accelerate the oxidation reaction taking place at low temperature. CuCeO_(2-x) nanorods catalyst shows promising competitive activity and ultra-low cost compared with the noble-based catalyst for the purification of hydrogen streams by the clean and eco-friendly sunlight sources.
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