| The growing environmental pollution has caused comprehensive concerns in scientific society.Due to the increase in population and industrialization,Waste generation has been greater than before as a repercussion of growing development and industrial development.Waste generation results in a variety of unwanted possessions on the environment as well as compromising human health by contaminating natural resources e,g,Water,air as well as soil.Pollution of Water and soil caused by the discharge of various such contaminants,mainly petrochemical contaminants,in the surroundings is a prominent public health concern because of toxicity with a relatively small concentration.So,there is an imperative requirement of the hours for decontamination of these hazardous substances from our environment.At the same time,the massive use of oil and other fossil fuels has led to several problems,such as rising average global temperature,an increasing greenhouse effect,and greenhouse gas emissions,especially carbon dioxide(CO2).Over the past century,the increase in CO2 concentration has led to a rise in global atmospheric temperature.At the current rate of increase,atmospheric CO2 levels are expected to reach 590 ppm by the 22 nd century and there is an urgent need to address the issue of reducing and releasing CO2 gases.Increasing environmental pollution has attracted the full attention of the scientific community.International authorities have published classifications related to pollutants and the adverse health consequences that can result from exposure to them,such as neurotoxicity,lung tumors,drowsiness,fatigue,depression,nausea,dizziness,and vertigo.The pollutants in this category consist mainly of toluene,benzene,xylene,ethylbenzene,and phenolic compounds,which are among the impurities that pose a serious risk to both the environment and the human body.Nowadays,there is a need to find an efficient,green,and low-cost method to reduce environmental pollutants or convert them into high-valueadded products.Photocatalysis is the most widely and potentially applied method used for the demineralization and degradation of these pollutants.In the photocatalytic degradation approach,various sources of light have been applied for the excitation of a heterogeneous catalyst.The photodegradation approach becomes more economical if sunlight is used as compared to ultraviolet light.The photodegradation of organic pollutants is an attractive green chemistry technology for pollution control.As an innovative and environmentally friendly approach,photocatalysis by light irradiation has been recognized to be very effective in the environmental remediation field.Thus,photocatalysis is considered a green approach technique for different pollutants degradation and generating electricity or fuel.Given that visible-light energy constitutes approximately 43% of solar energy,visible-light-responsive photocatalysts are chosen in photo-electro catalysis and photocatalysis.Photocatalysts can directly convert water into H2 and O2 under solar radiation and decrease CO2 into solar fuels.The enhancement of photocatalytic activity is closely related to the catalyst material’s structure,light absorption utilization,and charge separation efficiency capabilities,and the selection of suitable materials for modification and compounding is the key to enhancing its catalytic performance.In the last decade,graphitic carbon nitride is a model material that has seen widespread use for applications like water splitting,carbon dioxide reduction,and the degradation of contaminants.However,its limited visibility-light absorption and moderate surface catalysis mean it is still not widely used in photocatalytic conversion processes.Thus,it is widely more meaningful to further increase its photocatalytic activities to achieve an effective photocatalyst.Herein,we have carried out a series of modification strategies to improve charge separation,outspread the optical absorption to vis-light,and improve surface catalysis of g-C3N4 for boosted photocatalytic activities to obtain energyrich compounds and a safe environment for future generations.As part of this study,gC3N4 is coupled with materials Bi Fe O3 and Mn O2,respectively,to improve their charge separation ability and light absorption utilization,hence promoting the activity of photocatalytic reactions.Here are the key points:1.Synthesis of mediator free hollow Bi Fe O3 spheres/porous g-C3N4 Z-scheme photocatalysts for CO2 conversion and Alizarin Red S degradation.In this research work,we fruitfully prepared a mediator-free Bi Fe O3 hollow spheres/porous g-C3N4 Zscheme-based photocatalysts and the synthesized photocatalyst was employed for the conversion of CO2 and Alizarin Red S degradation.In this novel work,porous g-C3N4 was synthesized by acidic treatment and double calcination method.While hollow Bi Fe O3 spheres were synthesized using carbon nanospheres as a hard template material.The TEM results demonstrated that the P-CN has large pores and is thinner,while the particle size of hollow Bi Fe O3(HBFO)was determined to be around 200 nm to 500 nm.SEM tests observed a uniform distribution of HBFO particle size.BET tests showed that HBFO has a larger specific surface compared to Bi Fe O3 nanoparticles(BFO),with an increase in specific surface area for complex 6HBFO/P-CN(45.18 m2 g-1)compared to the precomposite material(30.87 m2 g-1).Based on characterization tests electrochemical impedance spectroscopy(EIS),SPS,and FS spectra reported to the produced ·OH amount,I-V curves,and UV-absorbance spectra,it was demonstrated that the coupling of hollow Bi Fe O3 spheres with porous g-C3N4 not only provides a thermodynamically suitable platform to facilitate photogenerated electron transfer but also enhances charge separation.UV-vis DRS spectroscopy verified that the 6HBFO/P-CN nanocomposite has better light absorption capability than the pre-composite material.Single-wavelength current density spectra(from 700 to 400 nm)were tested in visible light to demonstrate the charge and photoelectron transfer mechanism.6HBFO/P-CN nanocomposites showed a significant increase in photocurrent density at 450 nm,while the rise in 6HBFO/P-CN sustained photocurrent density demonstrated that HBFO and P-CN were instantaneously excited to generate photoelectrons from the PCN conduction band(CB)can be transferred to the valence band(VB)of HBFO and establish a Z-scheme,and the photoexcited electrons have a longer lifetime.It is confirmed that coupling of Bi Fe O3 hollow spheres with porous g-C3N4 not only thermodynamically provides a suitable platform for receiving the high energy level electrons but also enhanced charge separation.Compared to pristine P–CN,the most optimal sample,6HBFO/ P–CN,showed a 3.5-times enhancement in activities for Alizarin Red S decontamination and CO2 conversion under visible light irradiation.Finally,our present work will open a new gateway to synthesize Bi Fe O3 hollow spheres/porous g-C3N4 Z-scheme materials as effective photocatalysts for organic contaminants decontamination and CO2 conversion.2.Synthesis of Mn O2 coupled and metal oxide doped-C3N4 based polymeric nanocomposites for CO2 conversion and organic pollutants degradation.In this fruitful work,Porous C3N4 nanosheets were synthesized using dicyandiamide and NH4 Cl as precursor material and Chlorine intercalated porous C3N4 nanosheets were coupled with different mass percent ratios of Mn O2 nanoparticles and the formed nanocomposites were loaded with various percent ratios of porphyrin dye.various approaches were used to characterize the as prepared photocatalysts.Advanced X-ray powder diffraction patterns and XPS were used to investigate the crystalline phase,and the enhanced activity of the sample was confirmed via UV-vis DRS spectra.HRTEM was employed to investigate the morphologies of the nanocomposite of 0.701 nm MO fringes of d110 was successfully formed.Further,Steady-state surface photovoltage spectra(SPS)ascribed to photoexcited electrons transferred from CN to MO nanowires and doped porphyrin dye resulted in higher charge separation.The visible light absorption of the materials was significantly enhanced and the nano-photocatalysts were applied for the degradation of highly toxic phenol,2,4-dichlorophenol pollutants,and conversion of CO2.Compared to pristine CN,the most active sample 6MO/CN-20-CL showed 2.25-time progress in CO2 conversion.The degradation activities are greatly enhanced when doped with porphyrin dye.AS samp1 e 0.2D(6MO/CN-20C1)nanocomposite exhibited degradation rates of 47% and 60% for phenol and 2,4-dichlorophenol,respectively,within one hour under visible light.This is in contrast to the degradation activity of bare C3N4,which only achieved rates of 7% and 9%.The observed increase in degradation activities can be attributed to several factors,including the introduction of chlorine as inter-layer electron channels,resulting in increased internal layer conductivity.Additionally,the introduction of Mn O2 as a proper energy platform leads to improved charge separation due to heterojunction formation.Furthermore,the loading of a suitable volume of porphyrin dye as a visible light absorber extends optical absorption even up to 650 nm,as confirmed by photoluminescence spectra,the amount of produced hydroxyl radicals ·OH,and photoelectrochemical measurements.Based on trapping experiments,it has been verified that hydroxyl radicals ·OH are the primary species accountable for the degradation of 2,4-DCP. |
