Quantitative Analysis of Holmium Ion by a Ho3+ Ion‐Selective Sensor Based on a Symmetric Thio‐Schiff's Base

A poly(vinyl chloride) (PVC) membrane sensor for holmium ions was fabricated based on N‐[(Z)‐1‐(2‐thienyl)‐ methylidene]‐N‐[4‐(4‐{[(Z)‐1‐(2‐thienyl)methylidene]amino} phenoxy)phenyl] amine (TPA) as a new ion carrier, acetophenon (AP) as plasticizing solvent mediator and sodium tetraphenyl borate (NaTPB) as an anion excluder. The electrode shows a good selectivity towards Ho³⁺ ions respect to other inorganic cations, including alkali, alkaline earth, transition and heavy metal ions. The constructed sensor displays a Nernstian behavior (19.5±0.3 mV/decade) over the concentration range of 1.0×10⁻⁶ to 1.0×10⁻² mol·L⁻¹ with the detection limit of the electrode being 4.6×10⁻⁷ mol·L⁻¹ and very short response time (ca. 5 s). It has a useful working pH range of 3.2–9.8 for at least 8 weeks. The electrode was successfully applied as an indicator electrode for the potentiometric titration of a Ho³⁺ solution with EDTA and holmium determination in some alloys. The proposed sensor accuracy was studied by the determination of Ho³⁺ in mixtures of three different ions.     

Graphitic C3N4 Decorated with CoP Co‐catalyst: Enhanced and Stable Photocatalytic H2 Evolution Activity from Water under Visible‐light Irradiation

In this work, graphitic C₃N₄ decorated with a CoP co‐catalyst (g‐C₃N₄/CoP) is reported for photocatalytic H₂ evolution reaction based on two‐step hydrothermal and phosphidation method. The structure of g‐C₃N₄/CoP is well confirmed by XRD, FTIR, TEM, XPS, and UV/Vis diffuse reflection spectra techniques. When the weight percentage of CoP loading is 3.4 wt % (g‐C₃N₄/CoP‐3.4 %), the highest H₂ evolution amount of 8.4×10² μmol g⁻¹ is obtained, which is 1.1×10³ times than that over pure g‐C₃N₄. This value also is comparable with that of g‐C₃N₄ loaded by the same amount of Pt. In cycling experiments, g‐C₃N₄/CoP‐3.4 % shows a stable photocatalytic activity. In addition, g‐C₃N₄/CoP‐3.4 % is an efficient photocatalyst for H₂ evolution under irradiation with natural solar light. Based on comparative photoluminescence emission spectra, photoelectrochemical I –t curves, EIS Nyquist plots, and polarization curves between g‐C₃N₄/CoP‐3.4 % and pure g‐C₃N₄, it is concluded that the presence of the CoP co‐catalyst accelerates the separation and transfer of photogenerated electrons of g‐C₃N₄, thus resulting in improved photocatalytic activity in the H₂ evolution reaction.     

Direct Electrochemistry of Glucose Oxidase Immobilized on Titanium Carbide‐Au Nanoparticles‐Fullerene C60 Composite Film and Its Biosensing for Glucose

The direct electrochemistry of glucose oxidase (GOD) immobilized on the designed titanium carbide‐Au nanoparticles‐fullerene C₆₀ composite film modified glassy carbon electrode (TiC‐AuNPs‐C₆₀/GCE) and its biosensing for glucose were investigated. UV‐visible and Fourier‐transform infrared spectra of the resulting GOD/TiC‐AuNPs‐C₆₀ composite film suggested that the immobilized GOD retained its original structure. The direct electron transfer behaviors of immobilized GOD at the GOD/TiC‐AuNPs‐C₆₀/GCE were investigated by cyclic voltammetry in which a pair of well‐defined, quasi‐reversible redox peaks with the formal potential (E^0′) of ‐0.484 V (vs. SCE) in phosphate buffer solution (0.05 M, pH 7.0) at the scan rate of 100 mV·s^?1 were obtained. The proposed GOD modified electrode exhibited an excellent electrocatalytic activity to the reduction of glucose, and the currents of glucose reduction peak were linearly related to glucose concentration in a wider linearity range from 5.0 × 10^?6 to 1.6 × 10^?4 M with a correlation coefficient of 0.9965 and a detection limit of 2.0 × 10^?6 M (S/N = 3). The sensitivity and the apparent Michaelis‐Menten constant (K_M^app) were determined to be 149.3 μA·mM^?1·cm^?2 and 6.2 × 10^?5 M, respectively. Thus, the protocol will have potential application in studying the electron transfer of enzyme and the design of novel electrochemical biosensors.     

A Self‐assembled L‐Cysteine and Electrodeposited Gold Nanoparticles‐reduced Graphene Oxide Modified Electrode for Adsorptive Stripping Determination of Copper

Glassy carbon electrode (GCE) modified with L‐cysteine and gold nanoparticles‐reduced graphene oxide (AuNPs‐RGO) composite was fabricated as a novel electrochemical sensor for the determination of Cu²⁺. The AuNPs‐RGO composite was formed on GCE surface by electrodeposition. The L‐cysteine was decorated on AuNPs by self‐assembly. Physicochemical and electrochemical properties of L‐cysteine/AuNPs‐RGO/GCE were characterized by scanning electron microscopy, atomic force microscopy, energy dispersive spectroscopy, Raman spectroscopy, X‐ray diffraction, cyclic voltammetry and adsorptive stripping voltammetry. The results validated that the prepared electrode had many attractive features, such as large electroactive area, good electrical conductivity and high sensitivity. Experimental conditions, including electrodeposition cycle, self‐assembly time, electrolyte pH and preconcentration time were studied and optimized. Stripping signals obtained from L‐cysteine/AuNPs‐RGO/GCE exhibited good linear relationship with Cu²⁺ concentrations in the range from 2 to 60 μg L⁻¹, with a detection limit of 0.037 μg L⁻¹. Finally, the prepared electrode was applied for the determination of Cu²⁺ in soil samples, and the results were in agreement with those obtained by inductively coupled plasma mass spectrometry.     

Determination of Parathion‐methyl in Vegetables by Fluorescent‐Labeled Molecular Imprinted Polymer

A novel sensor for the determination of parathion‐methyl based on couple grafting of functional molecular imprinted polymers (MIPs) was fabricated which is developed by anchoring the MIP layer on surfaces of silica particles embedded CdSe quantum dots by surface imprinting technology. The synthesized molecular imprinted silica nanospheres (CdSe@SiO₂@MIP) allow a high selectivity and sensitivity of parathion‐methyl via fluorescence intensity decreasing when the MIP material rebinding the parathion‐methyl molecule. Compared with the MIP fabricated in traditional method, the template of parathion‐methyl was easier to remove from the CdSe@SiO₂@MIP imprinted material. Under optimal conditions, the fluorescence intensity of parathion‐methyl at the imprinted sensor was detected by spectrofluorophotometer. The relative fluorescence intensity of CdSe@SiO₂@MIP decreased linearly with the increasing concentration of parathion‐methyl ranging from 0.013 mg·kg⁻¹ to 2.63 mg·kg⁻¹ with a detection limit (3δ) of 0.004 mg·kg⁻¹ (S/N=3), which is lower than the MIP in tradition. The imprinted film sensor was applied to detect parathion‐methyl in vegetable samples without the interference of other organophosphate pesticides and showed a prosperous application in the field of food safety.     

Amperometric Biosensor for Detection of Phenolic Compounds Based on Tyrosinase,N‐Acetyl‐L‐cysteine‐capped Gold Nanoparticles and Chitosan Nanocomposite

A novel biosensor was fabricated based on the immobilization of tyrosinase and N ‐acetyl‐L ‐cysteine‐capped gold nanoparticles onto the surface of the glassy carbon electrode via the film forming by chitosan. The NAC‐AuNPs (N ‐acetyl‐L ‐cysteine‐capped gold nanoparticles) with the average size of 3.4 nm had much higher specific surface area and good biocompatibility, which were favorable for increasing the immobilization amount of enzyme, retaining the catalytic activity of enzyme and facilitating the fast electron transfer. The prepared biosensor exhibited suitable amperometric responses at −0.2 V for phenolic compounds vs. saturated calomel electrode. The parameters of influencing on the working electrode such as pH , temperature, working potential were investigated. Under optimum conditions, the biosensor was applied to detect catechol with a linear range of 1.0 × 10⁻⁷ to 6.0 × 10⁻⁵ mol•L⁻¹ , and the detection limit of 5.0 × 10⁻⁸ mol•L⁻¹ (S /N =3). The stability and selectivity of the proposed biosensor were also evaluated.     

Division Electrosynthesis of Palladium Nanomaterials with Copper–Graphene as Sacrificial Templates and Its Application for Hydrazine Sensing

One‐pot electrodeposited copper‐graphene (Cu‐GE ) nanocomposite acting as sacrificial template for the division electrosynthesis of palladium nanoparticles (PdNPs ) on pyrolytic graphite electrode (PGE ) was synthesized. The designed PdNPs‐GE nanocomposite was evaluated as a new material for highly sensitive determination of hydrazine (N₂H₄ ). Scanning electron microscopy revealed that the PdNP‐GE ‐modified PGE had uniform morphology. The results of energy‐dispersive X‐ray spectrograms confirmed the ingredients of the division electrosynthesis process. Electrochemical experiments were performed to characterize the sensing properties of PdNPs‐GE toward the electrocatalytic oxidation of N₂H₄ at 0.20 V in sodium phosphate buffered saline (0.1 M pH 7.0). The sensor showed fast response (<3 s), high sensitivity [398 (1 × 10⁻⁶ A) (1 × 10⁻³ M)⁻¹], and broad linearity in the range 2.5 × 10⁻⁸–2.7 × 10⁻⁴ M with a relatively low detection limit of 1.0 × 10⁻⁸ M (S/N = 3).     

Water Transport with Ultralow Friction through Partially Exfoliated g‐C3N4 Nanosheet Membranes with Self‐Supporting Spacers

Two‐dimensional (2D) graphitic carbon nitride (g‐C₃N₄) nanosheets show brilliant application potential in numerous fields. Herein, a membrane with artificial nanopores and self‐supporting spacers was fabricated by assembly of 2D g‐C₃N₄ nanosheets in a stack with elaborate structures. In water purification the g‐C₃N₄ membrane shows a better separation performance than commercial membranes. The g‐C₃N₄ membrane has a water permeance of 29 L m⁻² h⁻¹ bar⁻¹ and a rejection rate of 87 % for 3 nm molecules with a membrane thickness of 160 nm. The artificial nanopores in the g‐C₃N₄ nanosheets and the spacers between the partially exfoliated g‐C₃N₄ nanosheets provide nanochannels for water transport while bigger molecules are retained. The self‐supported nanochannels in the g‐C₃N₄ membrane are very stable and rigid enough to resist environmental challenges, such as changes to pH and pressure conditions. Permeation experiments and molecular dynamics simulations indicate that a novel nanofluidics phenomenon takes place, whereby water transport through the g‐C₃N₄ nanosheet membrane occurs with ultralow friction. The findings provide new understanding of fluidics in nanochannels and illuminate a fabrication method by which rigid nanochannels may be obtained for applications in complex or harsh environments.     

Square Wave‐Anodic Stripping Voltammetric Determination of Copper at a Bismuth Film/Glassy Carbon Electrode Using 3‐[(2‐Mercapto‐Vinyl)‐Hydrazono]‐ 1,3‐Dihydro‐Indol‐2‐One

This study reports a highly sensitive electrochemical sensor based on Bi film modified glassy carbon electrode (BiF/GCE) for total determination and speciation trace concentrations of copper(II) ions in environmental water samples. Square wave‐adsorptive anodic stripping voltammetric (SW‐ASV) experiment was performed for monitoring selective accumulation of copper(II) with reagent 3‐[(2‐mercapto‐vinyl)‐hydrazono]‐1,3‐dihydro‐indol‐2‐one (MHDI) at pH 9–10. The mechanism of the electrode reaction of Cu²⁺‐MHDI complex was safely assigned. The sensor exhibited a wide linear range (3.22×10⁻⁹–2.0×10⁻⁷ mol L⁻¹) with lower limits of detection (LOD) and quantitation (LOQ) of 9.6×1⁻¹⁰ and 3.22×10⁻⁹ mol L⁻¹, respectively (R²=0.9993). The proposed sensor exhibited interference from active metal ions e. g. Cd, Hg. The performance of the proposed method was compared successfully with most of the reported methods and comparable efficiencies were obtained. The analytical utility of the proposed SW‐ASV method has been successfully validated for trace analysis of copper(II) in environmental water samples. The method offers a precise, accurate approach with good reproducibility, robustness, ruggedness, and cost effectiveness.     

Development of an Electrochemical Sensor Based on Covalent Molecular Imprinting for Selective Determination of Bisphenol‐A

In this study, an electrochemical sensor was developed and used for selective determination of bisfenol‐A (BPA) by integrating sol‐gel technique and multi‐walled carbon nanotubes (MWCNTs) modified paste electrode. BPA bounded by covalently to isocyanatopropyl‐triethoxy silane (ICPTS) was synthesized as a new precursor (BPA‐ICPTS) and then BPA‐imprinted polymer (BPA‐IP) sol‐gel was prepared by using tetramethoxysilane (TMOS) and BPA‐ICPTS. Non‐imprinted polymer (NIP) sol‐gel was obtained by using TMOS and (3‐Aminopropyl) triethoxysilane. Both BPA‐IP and NIP sol‐gels were characterized by nitrogen adsorption‐desorption analysis, FTIR, SEM, particle size analyzer and optical microscope. Carbon paste sensor electrode was fabricated by mixing the newly synthesized BPA‐IP with MWCNTs, graphite powder and paraffin oil. The electrochemical characterization of the sensor electrode was achieved with cyclic and differential pulse voltammetric techniques. The response of the developed sensor under the most proper conditions was linear in BPA concentration range from 4.0×10⁻⁹ to 1.0×10⁻⁷ mol L⁻¹ and 5.0×10⁻⁷ to 5.0×10⁻⁵ mol L⁻¹ and the detection limit was 4.4×10⁻⁹ mol L⁻¹. The results unclosed that the proposed sensor displayed high sensitivity and selectivity, superior electrochemical performance and rapid response to BPA.     

The Hybrid of Gold Nanoparticles and 3D Flower‐like MnO2 Nanostructure with Enhanced Activity for Detection of Hydrogen Peroxide

3D Flower‐like manganese dioxide (MnO₂) nanostructure with the ability of catalysis for hydrogen peroxide (H₂O₂) and super large area that can support gold nanoparticles (AuNPs) with enhanced activity of electron transfer have been developed. The nanostructure of hybrids was prepared by directly mixing citric‐capped AuNPs and 3‐aminopropyltriethoxysilane (3‐APTES)‐capped nano‐MnO₂ using an electrostatic adsorption strategy. The Au‐MnO₂ composite was extensively characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), the Brunauer‐Emmett‐Teller (BET) method and X‐ray photoemission spectroscopy (XPS). Electrochemical properties were evaluated through cyclic voltammetry (CV) and amperometric method. The prepared sensor showed excellent electrochemical properties towards H₂O₂ with a wide linear range from 2.5×10⁻³∼1.39 mM and 3.89∼13.89 mM. The detection limit is 0.34 μM (S/N=3) with the sensitivities of 169.43 μA mM⁻¹ cm⁻² and 55.72 μA mM⁻¹ cm⁻². The detection of real samples was also studied. The result exhibited that the prepared sensor can be used for H₂O₂ detection in real samples.     

Tapioca Biofilm Containing Nitrogen‐doped Titanium Dioxide Nanoparticles for Electrochemical Detection of 17‐β Estradiol

A novel sensor architecture based on thin film of tapioca decorated within nitrogen‐doped titanium dioxide (N‐TiO₂) nanoparticles is reported. The nanostructures were characterized by scanning electron microscope, transmission electron microscope, X‐rays diffraction and voltammetric techniques. The proposed electrode was used for detection of low concentrations of 17‐β estradiol in without purification step, which was investigated by using linear sweep adsorptive stripping voltammetry. Under optimal conditions, the analytical curve was linear over a 17β‐estradiol concentration range of 9.9×10⁻⁶ to 1.4×10⁻⁵ mol L⁻¹, with a detection limit of 1.7×10⁻⁷ mol L⁻¹. The tapioca and N‐TiO₂ nanoparticles homogeneous film was applied for detection of 17‐β‐estradiol in tap water and synthetic urine samples, which presented satisfactory results.     

An Electrochemical Sensor Based on Reduced Graphene Oxide,Gold Nanoparticles and Molecular Imprinted Over‐oxidized Polypyrrole for Amoxicillin Determination

An electrochemical sensor for amoxicillin (AMX) detection based on reduced graphene oxide (RGO), molecular imprinted overoxidized polypyrrole (MIOPPy) modified with gold nanoparticles (AuNPs) is described in this work. The electrochemical behavior of the imprinted and non‐imprinted polymer (NIP) was carried out by cyclic voltammetry (CV) and impedance spectroscopy (IS). The structure and morphology of the prepared MIP sensor were characterized by scanning electron microscopy (SEM), UV‐Visible, Fourier transform infrared spectroscopy (FTIR) and its experimental parameters such as monomer and template concentration, pH buffer solution, incubation time of AMX and AuNPs, scan rate as well as electropolymerization scan cycles were optimized to improve the performance of the sensor. The peak current obtained at the MIP electrode was proportional to the AMX concentration in the range from 10^?8 to 10^?3 mol L^?1 with a detection limit and sensitivity of 1.22 10^?6 mol L^?1 (Signal to noise ratio=3) and 2.52×10^?6 μAmol^?1 L, respectively. It was also found that this sensor exhibited reproducibility and excellent selectivity against molecules with similar chemical structures. Besides, the analytical application of the AMX sensor confirms the feasibility of AMX detection in milk and human serum.     

Selective Electroanalysis of Ascorbic Acid Using a Nickel Hexacyanoferrate and Poly(3,4‐ethylenedioxythiophene) Hybrid Film Modified Electrode

The mixed‐valent nickel hexacyanoferrate (NiHCF) and poly(3,4‐ethylenedioxythiophene) (PEDOT) hybrid film (NiHCF‐PEDOT) was prepared on a glassy carbon electrode (GCE) by multiple scan cyclic voltammetry. The films were characterized using atomic force microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, X‐ray diffraction, and electrochemical impedance spectroscopy (AC impedance). The advantages of these films were demonstrated for the detection of ascorbic acid (AA) using cyclic voltammetry and amperometric techniques. The electrocatalytic oxidation of AA at different electrode surfaces, such as the bare GCE, the NiHCF/GCE, and the NiHCF‐PEDOT/GCE modified electrodes, was determined in phosphate buffer solution (pH 7). The AA electrochemical sensor exhibited a linear response from 5×10⁻⁶ to 1.5×10⁻⁴ M (R²=0.9973) and from 1.55×10⁻⁴ to 3×10⁻⁴ M (R²=0.9983), detection limit=1×10⁻⁶ M, with a fast response time (3 s) for AA determination. In addition, the NiHCF‐PEDOT/GCE was advantageous in terms of its simple preparation, specificity, stability and reproducibility.     

Molecularly Imprinted Electrochemical Sensor Based on Modified Reduced Graphene Oxide‐gold Nanoparticles‐polyaniline Nanocomposites Matrix for Dapsone Determination

This work was designed to develop an electrochemical sensor based on molecular imprinted polyaniline membranes onto reduced graphene oxide (RGO) and gold nanoparticles (AuNPs) modified glassy carbon (GC) electrode for dapsone (DDS) determination. The prepared RGO/AuNPs/PANI‐MIPs nanocomposite was characterized by Ultra‐Violet‐Visible (UV‐Vis), Fourier transform infrared spectroscopy (FT‐IR) and scanning electronic microscopy (SEM) images. The feature of the imprinted electrode was evaluated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and impedance spectroscopy (IS). Throughout this study several analytical parameters, such as incubation time, pH value, concentration of monomer/template molecules and electro‐polymerization cycles were investigated. Under the optimized conditions, the experimental results showed best analytical performances for DDS detection with a sensitivity of 0.188 Ω/mol L^?1, a linear range from 1.0×10^?7 M to 1.0×10^?3 M and a detection limit of 6.8×10^?7 M. The bioanalytical sensor was applied to the determination of dapsone in real samples with high selectivity and recovery.     

Copper Oxide Nanoparticles with Graphitic Carbon Nitride for Ultrasensitive Photoelectrochemical Aptasensor of Bisphenol A

In this work, g‐C₃N₄, CuO and g‐C₃N₄/CuO?X (where × can be 3, 6, or 9) were synthesized through hydrothermal and calcination methods and used to fabricate photoelectrochemical (PEC) aptasensor for detection of bisphenol A (BPA). CuO nanoparticles covered with g‐C₃N₄ were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The aptasensor based on g‐C₃N₄/CuO‐6 possessed high PEC activity due to its good conductivity and low electron recombination rate. PEC experiments demonstrate that the aptasensor based on g‐C₃N₄/CuO‐6 exhibits a broad linear range towards BPA from 0.02–10 ng L^?1 and 50–1200 ng L^?1 and reveals superior stability, selectivity and repeatability. Thus, g‐C₃N₄/CuO‐6 composite is a promising material for the determination of BPA in PEC field and has commercially viable.     

A Novel Electrochemical Sensor Based on Copper‐based Metal‐Organic Framework for the Determination of Dopamine

A glassy carbon electrode (GCE) modified with a copper‐based metal‐organic framework (MOF) [HKUST‐1, HKUST‐1 = Cu₃(BTC)₂ (BTC = 1,3,5‐benzenetricarboxylicacid)] was developed as a highly sensitive and simple electrochemical sensor for the determination of dopamine (DA). The MOF was prepared by a hydrothermal process, and the morphology and crystal phase of the MOF were characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD), respectively. Meanwhile, the electrochemical performance was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the modified electrode showed excellent electrocatalytic activity and high selectivity toward DA. The linear response range was from 5.0 × 10⁻⁷ to 1.0 × 10⁻⁴ M and the detection limit was as low as 1.5 × 10⁻⁷ M. Moreover, the electrochemical sensor was used to detect DA in real samples with excellent results. MOF‐based sensors hold great promise for routine sensing applications in the field of electrochemical sensing.     

Fe3O4@SiO2‐PANI‐Au Nanocomposite Prepared for Electrochemical Determination of Quercetin in Food Samples and Biological Fluids

A new electrochemical sensor based on Fe₃O₄@SiO₂‐PANI‐Au nanocomposite was fabricated for modification of glassy carbon electrode (Fe₃O₄@SiO₂‐PANI‐Au GCE). The Fe₃O₄@SiO₂‐PANI‐Au nanocomposite was characterized by TEM, FESEM‐EDS‐Mapping, XRD, and TGA methods. The Fe₃O₄@SiO₂‐PANI‐Au GC electrode exhibited an acceptable sensitivity, fast electrochemical response, and good selectivity for determination of quercetin. Under optimal conditions, the linear range for quercetin concentrations using this sensor was 1.0×10^?8 to 1.5×10^?5 mol L^?1, and the limit of detection was 3.8×10^?9 mol L^?1. The results illustrated that the offered sensor could be a possible alternative for the measurement of quercetin in food samples and biological fluids.     

A Sensitive and Renewable Chlortoluron Molecularly Imprinted Polymer Sensor Based on the Gate‐Controlled Catalytic Electrooxidation of H2O2 on Magnetic Nano‐NiO

A new sensor was fabricated by MIP synthesized on the surface of magnetic nickel(II) oxide (NiO) nanoparticles which based on the oxidation current change of H₂O₂. Chlortoluron was selected as template which can be detected indirectly by the decrease of the H₂O₂ oxidation current on the NiO nanoparticle‐modified GCE caused by the blocking access after rebinding. A high sensitivity was obtained because of the high catalytic effect of NiO nanoparticles on H₂O₂ oxidation. Chlortoluron was determined from 1.0×10^?8/L to 1.0×10^?4 mol/L, with a detection limit of 2.4×10^?9 mol/L. The proposed method combines the high sensitivity of the catalytic effect and the high selectivity of the MIP technique. Water samples were assayed using the MIP sensor, and recoveries of 96.9 % to 104.7 % were obtained.     

Enhanced Electrocatalytic Performance of a Porous g‐C3N4/Graphene Composite as a Counter Electrode for Dye‐Sensitized Solar Cells

A porous graphitic carbon nitride (g‐C₃N₄)/graphene composite was prepared by a simple hydrothermal method and explored as the counter electrode of dye‐sensitized solar cells (DSCs). The obtained g‐C₃N₄/graphene composite was characterized by XRD, SEM, TEM, FTIR spectroscopy, and X‐ray photoelectron spectroscopy. The results show that incorporating graphene nanosheets into g‐C₃N₄ forms a three‐dimensional architecture with a high surface area, porous structure, efficient electron‐transport network, and fast charge‐transfer kinetics at the g‐C₃N₄/graphene interfaces. These properties result in more electrocatalytic active sites and facilitate electrolyte diffusion and electron transport in the porous framework. As a result, the as‐prepared porous g‐C₃N₄/graphene composite exhibits an excellent electrocatalytic activity. In I^?/I₃^? redox electrolyte, the charge‐transfer resistance of the porous g‐C₃N₄/graphene composite electrode is 1.8 Ω cm², which is much lower than those of individual g‐C₃N₄ (70.1 Ω cm²) and graphene (32.4 Ω cm²) electrodes. This enhanced electrocatalytic performance is beneficial for improving the photovoltaic performance of DSCs. By employing the porous g‐C₃N₄/graphene composite as the counter electrode, the DSC achieves a conversion efficiency of 7.13 %. This efficiency is comparable to 7.37 % for a cell with a platinum counter electrode.