期刊：
ACS Applied Energy Materials,2024年7(13):5418–5425 ISSN：2574-0962
通讯作者：
Sun, LC;Sun, Licheng;Fan, K
作者机构：
[Sun, LC; Sun, Licheng; Ding, Yunxuan; Wang, Linqin] Westlake Univ, Ctr Artificial Photosynth Solar Fuels, Sch Sci & Res Ctr Ind Future, Hangzhou 310024, Peoples R China.;[Chai, Bo] Wuhan Polytech Univ, Sch Chem & Environm Engn, Wuhan 430023, Peoples R China.;[Sun, LC; Sun, Licheng; Ding, Yunxuan; Wang, Linqin] Westlake Univ, Res Ctr Ind Future, Sch Sci, Dept Chem, Hangzhou 310024, Peoples R China.;[Sun, LC; Sun, Licheng; Ding, Yunxuan; Wang, Linqin] Westlake Univ, Div Solar Energy Convers & Catalysis, Zhejiang Baima Lake Lab Co Ltd, Hangzhou 310000, Zhejiang, Peoples R China.;[Jia, Yufei; Fan, Ke; Sun, Licheng; Sun, LC; Li, Yaqing] Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth,Frontier Sci Ctr Smart, Inst Energy Sci & Technol,State Key Lab Fine Chem, Dalian 116024, Peoples R China.
通讯机构：
[Fan, K ; Sun, LC] D;[Sun, LC ] W;Westlake Univ, Ctr Artificial Photosynth Solar Fuels, Sch Sci & Res Ctr Ind Future, Hangzhou 310024, Peoples R China.;Westlake Univ, Res Ctr Ind Future, Sch Sci, Dept Chem, Hangzhou 310024, Peoples R China.;Westlake Univ, Div Solar Energy Convers & Catalysis, Zhejiang Baima Lake Lab Co Ltd, Hangzhou 310000, Zhejiang, Peoples R China.
摘要：
Bismuth-based catalysts have demonstrated significant electrocatalytic activity in the electrochemical CO2 reduction reaction (CO2RR) to produce formate/formic acid, while the morphology of these catalysts is considered to be crucial for their electrocatalytic performance. However, the potential topological transformation of Bi-based catalysts during CO2RR catalysis has been largely overlooked, which could lead to an underlying lack of understanding of the structure-activity relationship. In this study, various morphologies of bismuth sulfide (Bi2S3), including nanowires, nanoribbons, nanospheres, nanoparticles, and commercially available bulk powders of Bi2S3, were systematically investigated for the electrocatalytic CO2RR in a 1 M KOH electrolyte. Surprisingly, all of these morphologies exhibit excellent electrocatalytic activities for formate synthesis, with high Faradaic efficiencies exceeding 90%. Meanwhile, no significant distinction could be observed regarding their catalytic performance during long-term operation. During the CO2RR process, all Bi2S3 morphologies initially turn into similar nanocomposites of Bi and Bi2O2CO3 sheets, which subsequently undergo a topotactic transformation into metallic Bi nanoparticles. Theoretical calculations indicate that such a topotactic transformation is conducive to the CO2RR due to the superior activity and selectivity of metallic Bi nanoparticles. These findings shed light on the impact of the topotactic transformation of bismuth-based catalysts on the CO2RR, providing insights into the structure-activity relationship.
摘要：
Cr(VI) stands as a profoundly toxic chemical and photocatalysis technology has shown promising potential in photocatalytic reduction of Cr(VI) to Cr(III), where the reduced Cr(III) is less toxic and can be further precipitated in a wide pH range. Metal-organic frameworks (MOFs), as emerging class of porous coordination polymers, is expected to be ideal platform for photocatalysis. In this study, defect engineering on MOFs was applied to promote photoreduction of Cr(VI). The obtained oxygen vacancy-containing MIL-125-NH2 samples showed modified electron structure, adjusted surface and porous properties, and enriched active sites. Among these oxygen vacancy-containing MIL-125-NH2 samples, the 300-M (MIL-125-NH2 heated at 300 °C for 2 h under N2 atmosphere) displayed the most remarkable performance in terms of photocatalytic Cr(VI) reduction. The pronounced efficacy of 300-M is evident from the achieved removal rate of Cr (VI), reaching an impressive 98 % in just 20 mins (19.6 mgCr(VI) g−1cata min−1), in stark contrast to MIL-125-NH2, which exhibited a modest removal rate of 53 %. Remarkably, the k-value for 300-M is 5.1 times that of MIL-125-NH2, further underscoring the superior efficiency of 300-M. The photoreduction mechanism of 300-M was further substantiated through a battery of advanced characterization techniques including transient photocurrent, electrochemical impedance spectroscopy, fluorescence spectroscopy, the Mott-Schottky analysis, and electron spin resonance. Those results disclosed that oxygen vacancies and mesopores introduced via controlled heat treatment play a pivotal role in facilitating the photoreduction of Cr(VI) within the MIL-125-NH2 structure. More advanced characterizations for the structures of photocatalysts and the photocatalytic mechanisms including charge transfer path need further studied. The systematic exploration of temperature-dependent effects on material properties opens avenues for future research in designing efficient and versatile MOF-based photocatalysts for environmental remediation applications.
Cr(VI) stands as a profoundly toxic chemical and photocatalysis technology has shown promising potential in photocatalytic reduction of Cr(VI) to Cr(III), where the reduced Cr(III) is less toxic and can be further precipitated in a wide pH range. Metal-organic frameworks (MOFs), as emerging class of porous coordination polymers, is expected to be ideal platform for photocatalysis. In this study, defect engineering on MOFs was applied to promote photoreduction of Cr(VI). The obtained oxygen vacancy-containing MIL-125-NH2 samples showed modified electron structure, adjusted surface and porous properties, and enriched active sites. Among these oxygen vacancy-containing MIL-125-NH2 samples, the 300-M (MIL-125-NH2 heated at 300 °C for 2 h under N2 atmosphere) displayed the most remarkable performance in terms of photocatalytic Cr(VI) reduction. The pronounced efficacy of 300-M is evident from the achieved removal rate of Cr (VI), reaching an impressive 98 % in just 20 mins (19.6 mgCr(VI) g−1cata min−1), in stark contrast to MIL-125-NH2, which exhibited a modest removal rate of 53 %. Remarkably, the k-value for 300-M is 5.1 times that of MIL-125-NH2, further underscoring the superior efficiency of 300-M. The photoreduction mechanism of 300-M was further substantiated through a battery of advanced characterization techniques including transient photocurrent, electrochemical impedance spectroscopy, fluorescence spectroscopy, the Mott-Schottky analysis, and electron spin resonance. Those results disclosed that oxygen vacancies and mesopores introduced via controlled heat treatment play a pivotal role in facilitating the photoreduction of Cr(VI) within the MIL-125-NH2 structure. More advanced characterizations for the structures of photocatalysts and the photocatalytic mechanisms including charge transfer path need further studied. The systematic exploration of temperature-dependent effects on material properties opens avenues for future research in designing efficient and versatile MOF-based photocatalysts for environmental remediation applications.
摘要：
A series of Z-scheme TiO2/g-C3N4/RGO ternary heterojunction photocatalysts are successfully constructed via a direct electrospinning technique coupled with an annealing process for the first time. They are investigated comprehensively in terms of crystal structure, morphology, composition, specific surface area, photoelectrochemical properties, photodegradation performance, etc. Compared with binary TiO2/g-C3N4 and single-component photocatalysts, ternary heterojunction photocatalysts show the best photodegradation performance for RhB under stimulated sunlight. This can be attributed to the enlarged specific surface area (111.41 m2/g), the formation of Z-scheme heterojunction, and the high separation migration efficiency of photoexcited charge carriers. A potential Z-scheme mechanism for ternary heterojunction photocatalysts is proposed to elucidate the remarkably ameliorated photocatalytic performance based on active species trapping experiments, PL detection test of hydroxyl radicals, and photoelectrochemical properties.
摘要：
With increasing demands for clean and renewable energy, electrocatalytic water splitting is considered as the most promising procedure of hydrogen production. Pt is the best catalyst for the hydrogen evolution reaction (HER). However, the low oxygen evolution reaction (OER) activity of Pt prevents it from becoming a bifunctional catalyst in practical application. Ir-based electrocatalysts with good OER activities are expected to become the most promising bifunctional catalysts once their HER activities are improved. Herein, we report a simple synthesis of a Si-doped Ir electrode using magnetron sputtering. The physical and electrochemical characterization of the materials is achieved by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray fluorescence (XRF), X-ray diffraction (XRD) and X-ray photoelectron spectrometry (XPS). The electrochemical catalytic activity of the Si-doped Ir electrode toward the HER is demonstrated for the first time. Cyclic voltammetry (CV) curves reveal that the addition of Si can improve the utilization rate of Ir and result in a large electrochemical surface area (ESA). The overpotential of the Si-doped Ir electrode for the HER (eta = 114 mV, 50 mA cm(-2)) is obviously lower than that of an Ir electrode (eta = 148 mV, 50 mA cm(-2)) and very close to that of a Pt electrode (eta = 106 mV, 50 mA cm(-2)). The mass specific activity of the Si-doped Ir electrode exceeds that of an Ir electrode by a factor of ca. 2 at an overpotential of eta = 200 mV. The superior HER activity of the Si-doped Ir electrode could be attributed to the electronic structure modification of Ir by the interaction effect with Si as studied through XPS analysis. Moreover, the Tafel slope of 36.5 mV dec(-1) suggests that the mechanism for the Si-doped Ir electrode-catalyzed HER is Volmer-Tafel, in which the recombination of two adsorbed hydrogen atoms is the rate-determining step. In addition, the OER activity of the Si-doped Ir electrode outperforms that of an Ir electrode, which enables the Si-doped Ir electrode to be used as a bifunctional catalyst for overall water electrolysis.
摘要：
The Z-scheme photocatalysts of WO3/g-C3N4 composites with WO3 nanoplates anchored on the surface of g-C3N4 were synthesized by in-situ acidic precipitation and following calcination procedure. The resultant photocatalysts were characterized by various analytical techniques. This face-to-face intimate contact between g-C3N4 and plate-like WO3 not only increases the interfacial contact areas, but also facilitates the transfer and separation of photogenerated charge carriers. The photocatalytic activities of degradation Rhodamine (RhB) solution over WO3/g-C3N4 composites were evaluated under visible light irradiation. The enhanced photocatalytic activity of WO3/g-C3N4 composite could be attributed to the formation of the Z-scheme heterojunction system based on the active species trapping and hydroxyl radicals photoluminescence (PL) detection experiments. Furthermore, electrochemical impedance spectroscopy (EIS) and transient photocurrent measurements confirm the more efficient separation and transfer of photogenerated charge carriers on the WO3/g-C3N4 composite than that of pure WO3 or g-C3N4. This work would provide new insights into the design and preparation of face-to-face contact heterojunction photocatalysts for organic contaminant removal.
摘要：
TiO2-loaded Ti3C2 with small interlayer spacing [TiO2/Ti3C2(SIS)] was successfully synthesized through hydrothermal treatment and subsequent calcination under argon atmosphere. The phase composition, morphology and photophysical properties of Ti3C2, TiO2 and TiO2/Ti3C2(SIS) were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FSEM), transmission electron microscopy (TEM), UV–Vis spectrophotometry and fluorescence spectrophotometer, respectively. Furthermore, the photocatalytic activities of Ti3C2, TiO2 and TiO2/Ti3C2(SIS) were measured through monitoring photodegradation of methylene blue (MB) under ultraviolet (UV) light irradiation. The results showed that TiO2/Ti3C2(SIS) had an interfacial heterojunction between TiO2 and Ti3C2 with small interlayer spacing, leading to obviously improved optical absorbability and light quantum efficiency. Furthermore, the results of photocatalytic experiment indicated that TiO2/Ti3C2(SIS) exhibited significantly improved photocataytic activity compared with Ti3C2 and TiO2.
摘要：
Abstract To avoid deficiencies of traditional electrocoagulation process, electrocoagulation process powered by renewable photovoltaic energy has been directly used to remove nickel from wastewater. Results show that under the solar irradiation intensity (SII) of 750 ± 30 W/m2, aluminum electrode has higher nickel removal efficiency (NRE) than graphite and titanium, and its NRE is nearly 100% in 40 min. An optimum distance of 20 mm is determined for the electrode gap. NRE in 40 min nearly decreases from 99.6% to 78.8% when initial Ni2+ concentration increases from 100 to 300 mg/L. Under the SII of 610 ± 40 W/m2, solution containing SO42− of 3.4 mmol/L gets the highest NRE, while wastewater containing Cl− of 6.8 mmol/L has the lowest. Furthermore, effluent, including SO42− of 1.7 and Cl− of 3.4 mmol/L, shows a higher NRE too. NRE in 40 min increases when output power of the photovoltaic panel changes from 30 to 90 W, but doesn't show an obviously increasing tendency when the power improves further to 120 W. NRE for a fine day is the highest and is 100% in 40 min. However, its energy utilization efficiency is the lowest, but the saving cost is the most. In addition, MAl, Ct, and Ca sharply increase with the SII enhancing. Therefore, for some enterprises or regions with serious environmental burden and insufficient economic input, this process will provide an effective alternative approach to remove heavy metals from wastewater in a renewable and low-cost way.
