Asymmetric configuration activating lattice oxygen via weakening d-p orbital hybridization for efficient C/N separation in urea overall electrolysis

Urea oxidation reaction(UOR)is proposed as an exemplary half-reaction in renewable energy applications because of its low thermodynamical potential.However,challenges persist due to sluggish reaction kinetics and complex by-products separation.To this end,we introduce the lattice oxygen oxidation mechanism(LOM),propelling a novel UOR route using a modified CoFe layered double hydroxide(LDH)catalyst termed CFRO-7.Theoretical calculations and in-situ characterizations highlight the activated lattice oxygen(O_(L))within CFRO-7 as pivotal sites for UOR,optimizing the reaction pathway and accelerating the kinetics.For the urea overall electrolysis application,the LOM route only requires a low voltage of 1.54 V to offer a high current of 100 mA cm^(-2) for long-term utilization(>48 h).Importantly,the by-product NCO^(-)−is significantly suppressed,while the CO_(2)2/N_(2) separation is efficiently achieved.This work proposed a pioneering paradigm,invoking the LOM pathway in urea electrolysis to expedite reaction dynamics and enhance product selectivity.

Hydrothermal synthesis of CeO_2/NaNbO_3 composites with enhanced photocatalytic performance

A highly active photocatalyst CeO2/NaNbO3 is fabricated by a simple and facile hydrothermal method.The obtained photocatalyst composites are characterized by X‐ray powder diffraction,scanning electron microscopy,transmission electron microscopy and ultraviolet‐visible diffuse reflectance spectroscopy.The photocatalytic activity of the obtained samples is demonstrated by the photocatalytic degradation of the colorless antibiotic agent ciprofloxacin and the dye rhodamine B.The results reveal that CeO2/NaNbO3 composites exhibit a higher photocatalytic property than pure NaNbO3 under both UV and visible light irradiation.Furthermore,the optimum mass ratio of CeO2 in the CeO2/NaNbO3 composites is 2.0 wt%.The improved photocatalytic activity is attributed to the higher separation rate of the photo‐induced electrons and holes,and the higher migration rate of the photogenerated charge in the interfacial region.Furthermore,the photoluminescence pectra,photocurrent,electrochemical impedance spectroscopy and trapping experiment are applied to demonstrate the photocatalytic reaction mechanism of the as‐prepared samples.The result of the trapping experiment indicates that?OH radicals,?O2– radicals and holes are all involved in the photocatalytic degradation process of RhB.Furthermore,a possible mechanism for the enhancement of the photocatalytic activity is also proposed.

In situ single iron atom doping on Bi_(2)WO_(6)monolayers triggers efficient photo-fenton reaction

Developing an efficient photocatalytic system for hydrogen peroxide(H_(2)O_(2))activation in Fenton-like processes holds significant promise for advancing water purification technologies.However,challenges such as high carrier recombination rates,limited active sites,and suboptimal H_(2)O_(2)activation efficiency impede optimal performance.Here we show that single-iron-atom dispersed Bi_(2)WO_(6)monolayers(SIAD-BWOM),designed through a facile hydrothermal approach,can offer abundant active sites for H_(2)O_(2)activation.The SIAD-BWOM catalyst demonstrates superior photo-Fenton degradation capabilities,particularly for the persistent pesticide dinotefuran(DNF),showcasing its potential in addressing recalcitrant organic pollutants.We reveal that the incorporation of iron atoms in place of tungsten within the electron-rich[WO_(4)]^(2-)layers significantly facilitates electron transfer processes and boosts the Fe(II)/Fe(III)cycle efficiency.Complementary experimental investigations and theoretical analyses further elucidate how the atomically dispersed iron induces lattice strain in the Bi_(2)WO_(6)monolayer,thereby modulating the d-band center of iron to improve H_(2)O_(2)adsorption and activation.Our research provides a practical framework for developing advanced photo-Fenton catalysts,which can be used to treat emerging and refractory organic pollutants more effectively.

In-situ construction of Z-scheme g-C_(3)N_(4)/WO_(3) composite with enhanced visible-light responsive performance for nitenpyram degradation

Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field.Herein,a Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst was prepared by a facile in-situ calcination method,and the photocatalytic activity was investigated for degradation of nitenpyram(NTP)under visible light.The optimal Z-scheme WO_(3)/g-C_(3)N_(4) photocatalyst displayed the highest rate constant(0.036 min-1),which is about 1.7 and 25 times higher than that of pure g-C_(3)N_(4) and WO_(3),respectively.The improvement of photocatalytic performance is attributed to fast transfer of photogene rated carriers in the Z-scheme structure,which are testified by electron spin resonance(ESR)experiments,photocurrent and electrochemical impedance spectra(EIS)measurements.Moreover,the effects of typical water environmental factors on the degradation NTP were systematically studied.And the possible degradation pathways of NTP were deduced by the intermediates detected by highperformance liquid chro matography-mass spectrometry(HPLC-MS).This work will not only contribute to understand the degradation mechanism of pesticides in real water environmental condition,but also promote the development of new technologies for pesticide pollution control as well as environmental remediation.

0D/1D AgI/MoO_(3)Z-scheme heterojunction photocatalyst:Highly efficient visible-light-driven photocatalyst for sulfamethoxazole degradation

Low dimension nano photocatalysts show great potential in the field of treating contaminated water for their large surface area and size effect.In this study,a 0 D/1 D AgI/MoO_(3)Z-scheme photocatalyst with striking photocatalytic performance was constructed successfully.The one-dimensional MoO_(3)nanobelts were prepared by a simple hydrothermal method,and then it was modified by AgI nanoparticles in a handy deposition approach.When choosing sulfamethoxazole(SMZ)as the target contaminant,the rate constant value of the optimal 0 D/1 D AgI/MoO_(3)composite could hit up to 0.13 min^(-1),which is nearly 22.4 times and 32.5 times as that of pure MoO_(3)(0.0058 min^(-1))and AgI(0.0040 min^(-1)),respectively.A series of detailed characterizations give evidences that the charge transfer in the composite followed Z scheme mechanism.Therefore,efficient separation/transfer and the remained high redox activity of photogenerated carriers played a vital role in the sharply enhanced photocatalytic properties.The possible degradation pathways of SMZ were proposed based on the intermediates detected by high-performance liquid chromatography-mass spectrometry(HPLC-MS).Meanwhile,the magnificent cyclic stability makes the material a promising material in the practical application.

Mechanisms of photochemical release of dissolved organic matter and iron from resuspended sediments

Photochemical reactions can alter the transformation of sedimentary organic matter into dissolved organic matter(DOM)and affect its ultimate fate in water ecosystems.In the present study,the photorelease of DOM and Fe from resuspended lake sediments was investigated under different O_(2)and NO_(3)-concentration conditions to study the mechanisms of DOM and Fe photorelease.The amount of photoreleased Fe,which ranged from 0.22 to 0.70μmol/L,was significantly linearly correlated with the amount of photoreleased DOM.O_(2)and NO_(3)-could promote the photochemical release of DOM and Fe,especially during the initial 4 h irradiation.In general,the order of the photorelease rates of DOM and Fe under different conditions was as follows:NO_(3)-/aerobic>aerobic≈NO_(3)-/anaerobic>anaerobic.The photorelease rates of DOM and Fe were higher for the initial 4 hr irradiation than these for the subsequent 8 hr irradiation.The photorelease of DOM and Fe is thought to proceed via direct photodissolution and indirect processes.The relative contributions of indirect processes(>60%)was much greater than that of direct photodissolution(<40%).The photoproduced H 2 O_(2)under aerobic and anaerobic conditions indicated that hydroxyl radicals(·OH)are involved in the photorelease of DOM.Using·OH scavengers,it was found that 38.7%,53.7%,and 77.6%of photoreleased DOM was attributed to·OH under anaerobic,aerobic,and NO_(3)-/aerobic conditions,respectively.Our findings provide insights for understanding the mechanisms and the important role of·OH in the DOM and Fe photorelease from resuspended sediments.

Photocatalytic properties of P25-doped TiO_2 composite film synthesized via sol–gel method on cement substrate

TiO2 films have received increasing attention for the removal of organic pollutants via photocatalysis. To develop a simple and effective method for improving the photodegradation efficiency of pollutants in surface water, we herein examined the preparation of a P25-TiO2 composite film on a cement substrate via a sol–gel method. In this case, Rhodamine B（Rh B）was employed as the target organic pollutant. The self-generated TiO2 film and the P25-TiO2 composite film were characterized by X-ray diffraction（XRD）, N2 adsorption/desorption measurements, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, and diffuse reflectance spectroscopy（DRS）. The photodegradation efficiencies of the two films were studied by Rh B removal in water under UV（ultraviolet） irradiation. Over 4 day exposure, the P25-TiO2 composite film exhibited higher photocatalytic performance than the self-generated TiO2 film. The photodegradation rate indicated that the efficiency of the P25-TiO2 composite film was enhanced by the addition of the rutile phase Degussa P25 powder. As such, cooperation between the anatase TiO2 and rutile P25 nanoparticles was beneficial for separation of the photo-induced electrons and holes. In addition, the influence of P25 doping on the P25-TiO2 composite films was evaluated. We found that up to a certain saturation point, increased doping enhanced the photodegradation ability of the composite film. Thus, we herein demonstrated that the doping of P25 powders is a simple but effective strategy to prepare a P25-TiO2 composite film on a cement substrate, and the resulting film exhibits excellent removal efficiency in the degradation of organic pollutants.