超小荧光二硫化钨量子点的水热合成及细胞成像应用

以钨酸钠和半胱氨酸为原料, 采用水热法一步合成了具有超小粒径(约2 nm)的二硫化钨荧光量子点(WS₂ QDs). 利用透射电子显微镜(TEM)、 荧光光谱、 X射线光电子能谱(XPS)、 红外光谱(FTIR)和X射线衍射光谱(XRD)对其进行了表征, 并考察了其稳定性和细胞毒性. 结果表明, 制备的WS₂ QDs具有水溶性好、 稳定性高和细胞毒性低的优点. 将此WS₂ QDs用于人乳腺癌细胞(MCF-7)的成像, 并通过溶酶体荧光探针进行共定位, 发现此WS₂ QDs可能借助溶酶体进入细胞内.     

Ultrasonic-assisted exfoliation for 2D Zn(Bim)(OAc) nanosheets used as an oil-soluble additive in lubricants

The interface issue of two-dimensional (2D) nanomaterials has seriously restricted their applications in the past. To date, there have been few reports on the friction behavior of 2D MOFs. Herein, 2D Zn(Bim)(OAc) metal–organic framework structure nanosheets with a thickness of ca. 4 nm were successfully prepared via convenient ultrasonic-assisted exfoliation in solvents. For the first time, we probed the dispersion performance of the as-obtained 2D Zn(Bim)(OAc) in different oils, and intensively investigated the tribological behavior. The results indicated that the as-obtained 2D Zn(Bim)(OAc) used as an additive showed the preferable friction reducing performance and wear resistance in liquid paraffin, and showed the better dispersivity in glycerol.     

量子点自修饰TiO2p-n同质结的构建及光催化性能

在n型TiO₂纳米片表面原位沉积p型TiO₂量子点构建了量子点自修饰的TiO₂ p-n同质结(PNT-x), 并利用透射电子显微镜(TEM)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR)、 X射线光电子能谱(XPS)、 稳态荧光光谱(PL)、 拉曼光谱(Raman)、 紫外-可见漫反射光谱(UV-Vis DRS)、 电化学测试及电化学交流阻抗谱(EIS)对复合物的组成、 结构和光催化性能进行了表征和研究. 结果表明, PNT-x具有TiO₂量子点自修饰的结构, 量子点和纳米片中分别含有金属缺陷和氧缺陷, 其含量随组成变化可控, 并使得PNT-x表现出p-n同质结的典型特征, 与n-n Ⅱ型同质结以及块状p-n同质结相比, PNT-x中费米能级相差更大, 界面内电场更强, 具有更高的电荷分离和传递效率. 光照下, 样品的光催化活性顺序为PNT-400>p-25>PNT-600>PNT-200>p-TiO₂>n-TiO₂, 其中PNT-400的光催化产氢速率高达41.7 mmol·g^-1·h^-1, 分别为n-TiO₂纳米片、 Ⅱ型同质结和块状p-n同质结的4.3倍、 3.6倍和2.3倍, 并表现出优异的催化稳定性.     

Preparation and optical properties of three-dimensional navel-like Bi2WO6 hierarchical microspheres

Three-dimensional (3D) navel-like Bi₂WO₆ hierarchical microspheres were successfully prepared using a simple hydrothermal method. The 3D navel-like BWO hierarchical structure composed of well-ordered nanosheets displayed the excellent photocatalytic activity, and the degradation rate of norfloxacin was about 67%.     

基于WS2量子点材料固定葡萄糖氧化酶的直接电化学及其生物传感研究

采用水热法制备水溶性WS₂量子点（WS₂ QDs）材料,并将该材料进一步用于葡萄糖氧化酶（GOx）的有效固定,构建GOx/W₂ QDs/GCE传感界面. 采用透射电镜、紫外-可见光谱和电化学等方法对材料的形貌、GOx的固定化过程,以及传感器的直接电化学和电催化性能进行了表征. 结果表明,WS₂ QDs材料能够有效促进GOx与电极之间的直接电子转移. 并且,基于该传感器对葡萄糖良好的电催化作用,该方法有效实现了对葡萄糖的高灵敏检测,其线性范围为25 ~ 100 μmol·L^-1和100 ~ 600 μmol·L^-1,检测限为5.0 μmol·L^-1（S/N=3）. 该传感器具有良好的选择性、重现性和稳定性,可用于实际样品血糖的分析测定.     

一步原位还原法制备WS2@Au量子点复合物及其传感应用

电化学传感器界面改造是提升其检测性能的重要途径.其中,增强电化学传感界面的生物相容性和导电性,是电化学传感器发展遇到的一个重大挑战.本文基于一步原位还原法制备的WS2@Au量子点(WS2@AuQDs),对玻碳电极表面进行功能化,用于氧化还原酶的固定,实现了高性能生物传感的构建.借助WS2@Au QDs良好的生物相容性及...     

单层，少层和块状WS2薄膜中声子位移随温度的变化

Two-dimensional transition metal disulfides (TMDs) have recently attracted significant research attention due to their rich physical and chemical properties. Graphene has also been studied intensively due to its high electron mobility of ~200000 cm²·V⁻¹·s⁻¹. Since there is no band gap, it is difficult for a graphene-based device to achieve high current on/off ratio. For TMDs, such as MoS₂, MoSe₂, WSe₂, and WS₂, the band gaps of these materials can be adjusted according to the number of layers. Since TMD has the advantage of suppressing source-drain tunneling current in an ultra-short transistor and offering superior immunity to short-channel effects, it is also attractive for use as a channel material in Si complementary metal oxide semiconductor (CMOS) devices larger than 22 nm. Among them, MoS₂ in single-layer and multi-layer films have been intensively researched for many years. MoS₂-based field effect transistors (FETs) with excellent electrical properties have been reported. WS₂ has lower in-plane electronic mass than MoS₂, MoSe₂, and MoTe₂, and therefore has potential for higher carrier mobility or higher output current for WS₂-based FETs. Experimental research on WS₂ is limited compared to MoS₂, and more work is needed to further exploit the full potential of WS₂-based FETs. Therefore, the electron-phonon interaction and vibration properties of WS₂ used in nano-electronic applications and FETs must be investigated. To this end, mono-layer (1L), few-layer (FL), and bulk WS₂ films were prepared using mechanical exfoliation from a WS₂ crystal. 3M scotch-tape was used for transferring the WS₂ films. Detailed temperature-dependent Raman study on 1L, FL, and bulk WS₂ films has been conducted using a 514-nm excitation laser. Raman spectroscopy, as an effective and non-destructive approach for phonon vibration study, has been used to evaluate TMDs. The Raman spectra reveal much useful information on the test sample in terms of peak position and spectral shape change. With the film thickness increasing to bulk, the A_1g(Γ) and E_2g¹(Γ) modes show blue-shift and red-shift, respectively, with respect to 1L WS₂. Moreover, when the dominant Raman vibration modes swaps between E_2g¹(Γ) and A_1g(Γ), the "cross-over" temperature was identified for 1L, FL, and bulk WS₂ films. WS₂ shows smaller frequency change Δ between the E_2g¹(Γ) and A_1g(Γ) modes than MoS₂, with varying film thickness. The temperature coefficient of the Raman peak position was one magnitude lower for WS₂ than MoS₂, implying that WS₂ has better thermal stability than MoS₂. The results of this systematic study provide a physical guidance for WS₂-based device design.     

三元金属二硫化物纳米管的制备

1992年和 1 993年 ,Tenne等[1,2 ] 先后报道了具有类富勒烯和纳米管状结构的 WS2 和无机类富勒烯 Mo S2 .此后 ,无机类富勒烯化合物的制备与合成成为国内外学者的关注热点之一 .但采用化学方法制备纳米金属二硫化物时 ,多面体或洋葱状结构的 Mo S2 或 WS2 晶体的形成概率小 (这与碳的情况相似 ,也许通过扩展反应区内的温度梯度可以增加形成上述两种结构的可能性 [3] ) .另外 ,采用气固相反应制备洋葱状 WS2 的过程中 ,当每批次的量超过 1 5g时 ,无机类富勒烯 (IF)纳米颗粒的质量降低 ;同时 ,若滤筛中粉末厚度过大 ,相当大的凝聚团块开…     

Switch-on fluorescence sensor for ascorbic acid detection based on MoS2 quantum dots-MnO2 nanosheets system and its application in fruit samples

In this work,molybdenum disulfide quantum dots(MoS_2 QDs) were firstly prepared by hydrothermal method using sodium molybdate and glutathione as precursors,and applied in ascorbic acid detection.When joining MnO_2 nanosheets into MoS_2 QDs solution,they produced an obvious fluorescence quenching,which should be due to inner filter effect(IFE).Meanwhile,the fluorescent probe was formed,Interestingly,we found that this quenching phenomenon disappeared with the addition of ascorbic acid,In other words,the fluorescence gradually restored.This recovery phenomenon is mainly due to the reduction effect of ascorbic acid for MnO_2 nanosheets.Under the optimum conditions,the limit of detection(LOD) of 39 nmol/L for ascorbic acid was achieved with a linear range of 0.33-5.00 μmol/L.The repeatability was better than 5.0% for ascorbic acid in both standard and fruit samples(n = 3).Moreover,the as-fabricated fluorescent sensing system was successfully employed to detect the ascorbic acid levels in hawthorn and jujube with satisfactory results.     

Tribological properties of graphene nanosheets as an additive in calcium grease

The addition of graphene nanosheets (GNSs) in lubricating grease could significantly reduce the interfacial friction and improve the load-bearing capacity of the parts. Therefore, it has been considered as having great potential as lubricant additives. In this study, we synthesized GNSs that are prepared by a modified Hummer method, and investigated the effect of GNS with different concentration (0.5%, 1%, 2%, 3%, and 4?wt%) on the tribological properties of the calcium grease. The friction and wear experiments were performed using a four-ball tribometer. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were employed to examine the GNS and the friction mechanisms. Results indicate that the friction reduction ability and anti-wear property of the base grease can be improved with the addition of GNS. It was also found that the friction reduction decreases by 61%, and the wear scar diameter (WSD) decreases by 45%, and the extreme-pressure (EP) properties increased 60% at 3?wt% GNS. It is clear that the GNS in grease easily forms protective deposited films to prevent the rubbing surfaces from coming into direct contact, thereby improving the entire tribological behavior of the grease.     

Ni2P纳米片用于光催化二氧化碳还原

Artificial photosynthesis is an ideal method for solar-to-chemical energy conversion, wherein solar energy is stored in the form of chemical bonds of solar fuels. In particular, the photocatalytic reduction of CO₂ has attracted considerable attention due to its dual benefits of fossil fuel production and CO₂ pollution reduction. However, CO₂ is a comparatively stable molecule and its photoreduction is thermodynamically and kinetically challenging. Thus, the photocatalytic efficiency of CO₂ reduction is far below the level of industrial applications. Therefore, development of low-cost cocatalysts is crucial for significantly decreasing the activation energy of CO₂ to achieving efficient photocatalytic CO₂ reduction. Herein, we have reported the use of a Ni₂P material that can serve as a robust cocatalyst by cooperating with a photosensitizer for the photoconversion of CO₂. An effective strategy for engineering Ni₂P in an ultrathin layered structure has been proposed to improve the CO₂ adsorption capability and decrease the CO₂ activation energy, resulting in efficient CO₂ reduction. A series of physicochemical characterizations including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM) were used to demonstrate the successful preparation of ultrathin Ni₂P nanosheets. The XRD and XPS results confirm the successful synthesis of Ni₂P from Ni(OH)₂ by a low temperature phosphidation process. According to the TEM images, the prepared Ni₂P nanosheets exhibit a 2D and near-transparent sheet-like structure, suggesting their ultrathin thickness. The AFM images further demonstrated this result and also showed that the height of the Ni₂P nanosheets is ca 1.5 nm. The photoluminescence (PL) spectroscopy results revealed that the Ni₂P material could efficiently promote the separation of the photogenerated electrons and holes in [Ru(bpy)₃]Cl₂·6H₂O. More importantly, the Ni₂P nanosheets could more efficiently promote the charge transfer and charge separation rate of [Ru(bpy)₃]Cl₂·6H₂O compared with the Ni₂P particles. In addition, the electrochemical experiments revealed that the Ni₂P nanosheets, with their high active surface area and charge conductivity, can provide more active centers for CO₂ conversion and accelerate the interfacial reaction dynamics. These results strongly suggest that the Ni₂P nanosheets are a promising material for photocatalytic CO₂ reduction, and can achieve a CO generation rate of 64.8 μmol·h^-1, which is 4.4 times higher than that of the Ni₂P particles. In addition, the XRD and XPS measurements of the used Ni₂P nanosheets after the six cycles of the photocatalytic CO₂ reduction reaction demonstrated their high stability. Overall, this study offers a new function for the 2D transition-metal phosphide catalysts in photocatalytic CO₂ reduction.     

富含介孔Ni/W-USY/Al_2O_3催化剂的费托蜡加氢裂化性能

制备了富含介孔的Ni/W-USY/Al_2O_3催化剂并开展费托合成蜡加氢裂化实验,从反应性能、产品特性以及催化剂性质变化三方面对该催化剂进行评价。312 h运行实验结果表明,催化剂初始活性较高,120 h后趋于稳定,无明显失活现象,重质蜡转化率为73.95%时,轻质油选择性达到98.46%,裂解气以C_(3,4)为主;石脑油、煤油、柴油为无色透明液体,以正构烷烃和甲基、多甲基取代的异构烷烃为主,异构烃含量分别达到63.98%、52.26%、48.90%;对反应前后催化剂分析发现,新鲜催化剂的金属分散性较好、介孔含量高,加氢活性中心以WS_2、NiWS为主,随着反应由高活性到稳定阶段过渡,WS_2部分迁移并与Ni形成更多Ni-S-W键,部分W-S键断裂释放出S后形成W-W键,使得稳定后催化剂的NiWS活性中心增加而WS_2活性中心降低,并引起L酸密度降低而B酸密度增加。     

二维材料膜在气体分离领域的最新研究进展

Two-dimensional (2D) materials, led by graphene, have emerged as nano-building blocks to develop high-performance membranes. The atom-level thickness of nanosheets makes a membrane as thin as possible, thereby minimizing the transport resistance and maximizing the permeation flux. Meanwhile, the sieving channels can be precisely manipulated within sub-nanometer size for molecular separation, such as gas separation. For instance, graphene oxide (GO) channels with an interlayer height of about 0.4 nm assembled by external forces exhibited excellent H₂/CO₂ sieving performance compared to commercial membranes. Cross-linking was also employed to fabricate ultrathin (< 20 nm) GO-facilitated transport membranes for efficient CO₂ capture. A borate-crosslinked membrane exhibited a high CO₂ permeance of 650 GPU (gas permeation unit), and a CO₂/CH₄ selectivity of 75, which is currently the best performance reported for GO-based composite membranes. The CO₂-facilitated transport membrane with piperazine as the carrier also exhibited excellent separation performance under simulated flue gas conditions with CO₂ permeance of 1020 GPU and CO₂/N₂ selectivity as high as 680. In addition, metal-organic frameworks (MOFs) with layered structures, if successfully exfoliated, can serve as diverse sources for MOF nanosheets that can be fabricated into high-performance membranes. It is challenging to maintain the structural and morphological integrity of nanosheets. Poly[Zn₂(benzimidazole)₄] (Zn₂(bim)₄) was firstly exfoliated into 1-nm-thick nanosheets and assembled into ultrathin membranes possessing both high permeance and excellent molecular sieving properties for H₂/CO₂ separation. Interestingly, reversed thermo-switchable molecular sieving was also demonstrated in membranes composed of 2D MOF nanosheets. Besides, researchers employed layered double hydroxides (LDHs) to prepare molecular-sieving membranes via in situ growth, and the as-prepared membranes showed a remarkable selectivity of ~80 for H₂-CH₄ mixture. They concluded that the amount of CO₂ in the precursor solution contributed to LDH membranes with various preferred orientations and thicknesses. Apart from these 2D materials, MXenes also show great potential in selective gas permeation. Lamellar stacked MXene membranes with aligned and regular sub-nanometer channels exhibited excellent gas separation performance. Moreover, our ultrathin (20 nm) MXene nanofilms showed outstanding molecular sieving property for the preferential transport of H₂, with H₂ permeance as high as 1584 GPU and H₂/CO₂ selectivity of 27. The originally H₂-selective MXene membranes could be transformed into membranes selectively permeating CO₂ by chemical tuning of the MXene nanochannels. This paper briefly reviews the latest groundbreaking studies in 2D-material membranes for gas separation, with a focus on sub-nanometer 2D channels, exfoliation of 2D nanosheets with structural integrity, and tunable gas transport property. Challenges, in terms of the mass production of 2D nanosheets, scale-up of lab-level membranes and a thorough understanding of the transport mechanism, and the potential of 2D-material membranes for wide implementation are briefly discussed.     

构筑先进二维异质结构Ag/WO3−x用于提升光电转化效率

Solar energy, which is clean, affordable and reliable, can help alleviate the current environmental pollution and energy crisis efficiently. In the past few decades, great progress has been made in harvesting and converting solar energy into chemical energy. Among various technologies, plasmon-induced photoelectrochemistry has been proposed as a promising alternative for solar energy conversion. The hot electrons generated from plasmon excitation and transfer from metal nanostructures to semiconductors is a potential new paradigm for solar energy conversion. However, the ultrafast decay of the hot carriers is unfavorable for the improvement of photocatalytic efficiency. Therefore, finding more efficient photocatalysts, with enhanced light absorption and a longer carrier lifetime, is of paramount importance for improving the conversion efficiency of solar energy, but their fabrication is challenging. In this work, a plasmonic metal/semiconductor heterostructure based on Ag nanoparticles embedded in two-dimensional (2D) amorphous sub-stoichiometric tungsten trioxide (a-WO_3−x), followed by annealing, was successfully fabricated. Firstly, the peculiar nanostructure of 2D a-WO_3−x was successfully constructed from WS₂ nanosheets with supercritical CO₂ (SC CO₂) at 200 ℃. Secondly, the Ag/a-WO_3−x heterostructure was synthesized using an in situ reduction method. Finally, the obtained 2D heterostructure of Ag/WO_3−x was annealed at 400 ℃ in N₂ to further improve its stability and conductivity. X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure, morphology, and composition of the material, respectively. UV-Vis spectra were also measured to evaluate light adsorption. Characterization results show that the amorphous structure can effectively anchor metal nanoparticles, and the metal nanoparticles are uniformly dispersed in the amorphous region and have a small size. The as-prepared nanocomposites showed efficient photoelectrochemical (PEC) water splitting when serving as photoelectrode materials, and efficient PEC activity towards photo-oxidation degradation currents under excitation of Ag localized surface plasmon resonance (LSPR). The photocurrent response of the Ag/WO_3−x heterostructure was approximately five times greater than that of a-WO_3−x. Moreover, the PEC degradation efficiency of Ag/WO_3−x reached 96.7% for MO under Vis light illumination (after reaction for 120 min), while the PEC degradation efficiency of WO_3−x was only 63.6%. The high PEC performance of the composite photoanode can be ascribed to the local surface plasmon resonance (LSPR) effect of the Ag nanoparticles, which can enhance the light absorption and hot electron transformation. Moreover, the construction of local crystalline-amorphous interfaces can further promote the separation efficiency of the photogenerated electron-hole pairs, and thus increase conductivity. This work provides a positive strategy for the fabrication of advanced photocatalysts, and a new perspective on understanding of the synergistic effects of structural and electronic regulations.     

CuInS_2量子点敏化太阳能电池中尺寸依赖的电子注入和光电性质

研究了CuInS2(CIS)量子点敏化太阳能电池(QDSSCs)的电子注入和器件性能与粒子尺寸之间的依赖关系.首先合成了不同尺寸的CuInS2量子点(QDs),制备了CuInS2量子点敏化的TiO2薄膜,并组装了量子点敏化太阳能电池.通过循环伏安法确定了CuInS2量子点的能级位置.采用时间分辨荧光光谱分析测量了CuInS2量子点到TiO2薄膜的电子转移速率和效率.结果发现,随着粒子尺寸从4.0 nm减小到2.5 nm,电子注入速率略微增加而电子注入效率减小,同时量子点敏化太阳能电池的开路电压基本不变,而光电转换效率、短路电流和填充因子(FF)均减小.上述研究结果表明量子点敏化太阳能电池性能的优化可以通过改变量子点的尺寸来实现.     

Cu_2O@HKUST-1前驱物法合成CuO中空管状超级结构及其CO催化氧化性能

以Cu_2O@HKUST-1(HKUST-1=Cu_3(BTC)2,BTC~(3-)=均苯三甲酸离子)线状核@壳结构为前驱体,通过在碱性条件下原位水解HKUST-1壳、氧化刻蚀Cu_2O核的方法得到了一种新型的、由相互交错的CuO纳米片构筑的、中空管状的超级结构,并研究了其对CO氧化的催化活性。结果表明,这种中空的CuO管状超级结构具有较大的比表面积(56.3 m~2/g)和可观的催化活性,催化剂对CO的完全转化温度为200℃,190℃时转化效率为17.3 mmolCO/(gCuO·h)。     

Investigation of tribological properties of Al2O3-polyimide nanocomposites

Polyimide (PI) nanocomposites with different proportions of nanoparticle Al₂O₃ were made by compression molding at elevated temperature. The mechanical and tribological properties of the resulting PI-based nanocomposites were investigated. The bending strength and microhardness of the nanocomposite specimens were determined, and the tribological behavior of the nanocomposite blocks in dry sliding against a plain carbon steel ring was evaluated on an M-2000 friction and wear tester. The morphologies of the worn nanocomposite surfaces and transfer films on the counterpart steel ring were observed on a scanning electron microscope. Results indicated that the PI-based nanocomposites with appropriate proportions of nanometer Al₂O₃ exhibited lower friction coefficient and wear volume loss than PI under the same testing conditions. The nanocomposite containing 3.0wt.%–4.0wt.% nanometer Al₂O₃ registered the lowest wear volume loss under a relatively high load. The differences in the friction and wear behaviors of PI and PI–Al₂O₃ nanocomposites were attributed to the differences in their worn surface morphologies, transfer film characteristics, and wear debris features. The agglomerated abrasives on the worn composite and transfer film surfaces contributed to increase the wear volume loss of the nanocomposites of higher mass fractions of nanometer Al₂O₃.     

基于二维材料WX_2构建的范德华异质结的结构和性质及应变效应的理论研究

二维材料过渡金属硫属化物(TMDs),因其优越的物理化学特性及其在光电子器件、光催化等领域的潜在应用价值,得到了人们的广泛关注。基于TMDs材料可以构建具有不同性能的范德华(vdW)异质结,但构建的异质结由于其固有的能带带隙大小限制了其在全光谱上的响应,因而对其能带带隙调控变得十分重要。本文基于第一性原理方法系统地研究了WX_2 (X=S, Se, Te)从单层到体相的结构和性质,以及由此组装的vdW异质结构WS_2/WSe_2、WS_2/WTe_2和WSe_2/WTe_2的结构和性质以及应力应变对异质结构的能带带隙的影响。结果表明:结合HSE06泛函和自旋轨道耦合(SOC)效应的计算方案可以精确描述WX_2体系;异质结构WS_2/WSe_2,WS_2/WTe_2和WSe_2/WTe_2呈现type-II能带分类;在施加单轴或双轴的应力应变后,能带带隙大小发生相应改变,当晶格形变大于4%后,异质结构由半导体特性变成具有金属性。这些研究为光电子器件的设计提供了重要的指导意义。     

自支撑NiFe LDHs@Co-OH-CO3纳米棒阵列电极用于碱性阴离子交换膜电解水

开发高效耐用的电极对碱性阴离子交换膜电解水（AEMWEs）制氢至关重要。在这项研究中,我们展示了一种高效且稳定的自支撑NiFe LDHs@Co-OH-CO₃/NF纳米棒阵列电极分别用于析氧反应（OER）和AEMWE的阳极。在这项工作中,我们将2D的镍铁层状双金属氢氧化物纳米片（NiFe LDHs）原位生长在1D的碱式碳酸钴纳米线上（Co-OH-CO₃/NF）,最终得到独特的纳米棒阵列复合结构电极。在三电极体系中,自支撑NiFe LDHs@Co-OH-CO₃/NF对OER具有良好的催化活性, 在1 mol·L^-1 KOH中, 当电流密度为20 mA·cm^-2时,过电位为215 mV。当自支撑NiFe LDHs@Co-OH-CO₃/NF作为AEMWE的阳极（70 ^oC,1 mol·L^-1 KOH）,在电流密度为0.5 A·cm^-2时, 电解电压为1.72 V,并且具有较好的稳定性。进一步的实验表征结果显示了自支撑NiFe LDHs@Co-OH-CO₃/NF的优异性能是其具有特殊的形貌结构。这是由于纳米棒阵列电极的三维分层结构可以有效防止纳米片团聚, 从而有利于电子转移,为水分解提供大量的边缘活性位点。     

二维/二维FeNi-LDH/g-C3N4复合光催化剂用于促进CO2光还原反应

Photocatalytic reduction of carbon dioxide into chemical fuels is a promising route to generate renewable energy and curtail the greenhouse effect. Therefore, various photocatalysts have been intensively studied for this purpose. Among them, g-C₃N₄, a 2D metal-free semiconductor, has been a promising photocatalyst because of its unique properties, such as high chemical stability, suitable electronic structure, and facile preparation. However, pristine g-C₃N₄ suffers from low solar energy conversion efficiency, owing to its small specific surface area and extensive charge recombination. Therefore, designing g-C₃N₄ (CN) nanosheets with a large specific surface area is an effective strategy for enhancing the CO₂ reduction performance. Unfortunately, the performance of CN nanosheets remains moderate due to the aforementioned charge recombination. To counter this issue, loading a cocatalyst (especially a two-dimensional (2D) one) can enable effective electron migration and suppress electron-hole recombination during photo-irradiation. Herein, CN nanosheets with a large specific surface area (97 m²·g^-1) were synthesized by a two-step calcination method, using urea as the precursor. Following this, a 2D/2D FeNi-LDH/g-C₃N₄ hybrid photocatalyst was obtained by loading a FeNi layered double hydroxide (FeNi-LDH) cocatalyst onto CN nanosheets by a simple hydrothermal method. It was found that the production rate of methanol from photocatalytic CO₂ reduction over the FeNi-LDH/g-C₃N₄ composite is significantly higher than that of pristine CN. Following a series of characterization and analysis, it was demonstrated that the FeNi-LDH/g-C₃N₄ composite photocatalyst exhibited enhanced photo-absorption, which was ascribed to the excellent light absorption ability of FeNi-LDH. The CO₂ adsorption capacity of the FeNi-LDH/g-C₃N₄ hybrid photocatalyst improved, owing to the large specific surface area and alkaline nature of FeNi-LDH. More importantly, the introduction of FeNi-LDH on the CN nanosheet surface led to the formation of a 2D/2D heterojunction with a large contact area at the interface, which could promote the interfacial separation of charge carriers and effectively inhibit the recombination of the photogenerated electrons and holes. This subsequently resulted in the enhancement of the CO₂ photo-reduction activity. In addition, by altering the loading amount of FeNi-LDH for photocatalytic performance evaluation, it was found that the optimal loading amount was 4% (w, mass fraction), with a methanol production rate of 1.64 μmol·h^-1·g^-1 (approximately 6 times that of pure CN). This study provides an effective strategy to improve the photocatalytic CO₂ reduction activity of g-C₃N₄ by employing 2D layered double hydroxide as the cocatalyst. It also proposes a protocol for the successful design of 2D/2D photocatalysts for solar energy conversion.