A facile synthesis of metal ferrites (MFe2O4, M = Co,Ni, Zn,Cu) as effective electrocatalysts toward electrochemical hydrogen evolution reaction

Developing low-cost, stable, and robust electrocatalysts for hydrogen evolution reaction (HER) is highly desirable for large-scale application. In this study, a highly efficient electrocatalysts of metal ferrites (MFe₂O₄, M = Co, Ni, Zn, Cu) with superior activity and durability are successfully fabricated on copper substrate through a facile co-precipitation method followed by doctor-blading deposition. The electrocatalytic performance of CoFe₂O₄, NiFe₂O₄, ZnFe₂O₄ and CuFe₂O₄ electrodes for hydrogen evolution reaction is studied in alkaline media using polarization curves and electrochemical impedance spectroscopy (EIS). Among them, CoFe₂O₄ presented the best electrocatalytic activities for HER with extremely low overpotentials of 270 mV (vs. RHE) at a current density of 10 mA cm^?2 in 1 M KOH. The electrocatalytic activity of MFe₂O₄ (M = Co, Ni, Zn, Cu) for HER to generate current density of 10 mA cm^?2 with low overpotential followed the order of CoFe₂O₄ > CuFe₂O₄ > NiFe₂O₄ > ZnFe₂O₄. The highly improved HER performance of CoFe₂O₄ is mainly due to a large number of exposed active sites, high electrical conductivity and low apparent activation energy, which are confirmed by a remarkable electrochemically active surface area (ECSA = 53.17 cm²), Nyquist plots analysis and Arrhenius plots measurement, respectively. Moreover, the CoFe₂O₄ electrode showed outstanding electrocatalytic stability even after 1000 cyclic voltametry tests. These results provide a promising avenue for developing cost-effective and high-efficiency electrocatalysts based on earth-abundant transition metal ferrite as advanced electrodes for large-scale energy conversion processes.     

Study of NiFe2O4 nanoparticles optical properties by a six-flux radiation model towards the photocatalytic hydrogen production

At present, synthesis of visible-light active materials for hydrogen production through water splitting has become one of the most important challenges in photocatalysis. Of equal importance, photocatalyst optical properties are essential information in order to determine reaction kinetics involved in water splitting. Transition metals spinel ferrites MFe₂O₄ exhibit remarkable activity under visible light for this reaction. However, their optical properties have not been fully determined in photocatalytic kinetic studies. In this research, synthesized and commercial NiFe₂O₄ nanoparticles were compared. NiFe₂O₄ was synthesized by the Pechini method and both materials were studied: structural, textural and optical characterization was performed through XRD, TEM, TGA, BET surface area and UV/Vis spectroscopy and photocatalytic evaluation was performed for hydrogen production. NiFe₂O₄ optical properties were determined by UV/Vis spectroscopy and using a simplified theoretical model for the Radiative Transfer Equation (RTE) called Six-Flux Model (SFM). All performed characterizations and obtained coefficients for the ferrites were compared finding differences between absorption and scattering coefficients, which were attributed to the porosity of the synthesized ferrite.     

Boosting the kinetics of oxygen and hydrogen evolution in alkaline water splitting using nickel ferrite /N-graphene nanocomposite as a bifunctional electrocatalyst

Design, synthesize and application of metal-oxide based bifunctional electrocatalysts with sustainability and efficient activity in water splitting is significant among the wide spread researches in energy applications. Herein, bifunctional electrocatalysts composed of NiFe₂O₄ dispersed on N-doped graphene has been prepared by in-situ polymerization and characterized for further bifunctional catalytic performances. The electrocatalyst exhibited bespoken performances as cathode in HER as well as anode in OER at alkaline electrolyte. The nanocomposite N-doped graphene/NiFe₂O₄ (NGNF) exhibited low overpotential of 184 mV in HER and 340 mV in OER for attaining the current density of 10 mA/cm² which is far better than their pristine counterparts. Similarly its Tafel slopes were found to be 82.9 mV/dec and 93.2 mV/dec for HER and OER. As an electrocatalyst NGNF outperformed pure nickel ferrite and graphene/NiFe₂O₄ (GNF) as bifunctional electrocatalyst with low overpotential and Tafel slopes. This indicates the impact of graphene and N-doping on graphene in the activity of pure NF. The graphene in the composite and the N-dopants provoked the catalytic activity and tuned the electron transfer and interaction with the electrolyte. Thus, herein we endow with strategies of preparing highly efficient bifunctional electrocatalysts by coupling spinel oxides and N-doped graphene for HER and OER.     

Facile reduction of nitrophenols: Comparative catalytic efficiency of MFe2O4 (M = Ni,Cu, Zn) nano ferrites

Nano ferrites of the formula MFe₂O₄ (M = Ni, Cu, Zn), synthesized using sol–gel technique, were employed to catalyze the reductive transformation of nitrophenols to aminophenols. The catalytic reduction was carried out in the excess of NaBH₄ as reducing agent in aqueous medium at room temperature. CuFe₂O₄ and NiFe₂O₄ were found to be active for the reduction of nitrophenols with significant difference in their activities whereas ZnFe₂O₄ was found to be inactive. The kinetics of the reduction of nitrophenols to aminophenols was also investigated. The reaction followed pseudo first order kinetics. The first order rate constant values for 30 mol% of CuFe₂O₄ and NiFe₂O₄ for the reduction of 2-nitrophenol were observed to be 3.68 min⁻¹ and 0.33 min⁻¹ respectively. The rates of reduction for the three isomers of nitrophenol were also studied and were observed to follow the order – 2-nitrophenol > 4-nitrophenol > 3-nitrophenol. The selective formation of aminophenol was confirmed using LC-MS, ¹H NMR and FT-IR spectroscopic techniques.     

A promising synergistic effect of nickel ferrite loaded on the layered double hydroxide-derived carrier for enhanced photocatalytic hydrogen evolution

In this study, an attempt was made to modify the photocatalytic properties of an ion-exchangeable semiconductor material to enhance the efficiency of hydrogen production. Visible-light active NiFe₂O₄ was loaded onto NiZn/Cr layered double hydroxide (LDH) (Ni/Zn molar ratio = 75/25) with the Fe/Cr molar ratio of 0.005, 0.010, and 0.015 as cocatalyst through a simple solvothermal process and subsequently subjected to calcination at temperature of 500 °C. The results revealed that the presence of the loaded cocatalyst significantly facilitated the photocatalytic activity and the mixed oxide with Fe/Cr = 0.010 displayed the highest photocatalytic activity for visible light-induced H₂ generation. The optimal amount of hydrogen evolution reached to 269.44 μmolh^?1 under visible light (λ > 420 nm), which is far superior to that of the pristine NiZn/Cr LDH-derived oxides material (130.85 μmolh^?1), indicating the important catalytic role of NiFe₂O₄. The significant enhancement in photoactivity was attributed to the synergistic effect of nickel ferrite attached on the external surface of the calcined brucite-like sheets of the LDH. The cocatalyst NiFe₂O₄ nanoparticles increase the donor or acceptor levels in comparison with the pristine NiZn/Cr LDH-derived semiconductor oxide. Moreover, the existence of sheet-like LDH-derived carrier could inhibit the rapid recombination of photogenerated electrons and holes.     

Phosphate ions-functionalized and wettability-tuned nickel ferrite for boosted oxygen evolution performance

Nickel ferrite (NiFe₂O₄) has been explored as a promising oxygen evolution reaction (OER) electrocatalyst for water splitting owning to its earth-abundant and considerable water oxidation catalytic activity. Nevertheless, its practical electrocatalytic performance towards OER is still undesirable due to the sluggish OER kinetics and high overpotential gap on the water oxidation anode side. In this work, in order to enhance the electrochemical water oxidation performance of NiFe₂O₄, the surface of NiFe₂O₄ is functionalized with phosphate ions (Pi) by using a facile incipient impregnation and following calcination process. Results demonstrate that the OER properties of NiFe₂O₄ under alkaline conditions can be dramatically boosted by the surface Pi functionalization. In 1.0 M KOH solution, the resulting NiFe₂O₄-Pi on glassy carbon (GC) electrode demonstrates quite lower overpotential of 332 mV (10 mA/cm²) and Tafel slope of 57 mV/dec compared to that of pristine NiFe₂O₄ (443 mV@10 mA/cm² and 96 mV/dec), which is also better than that of commercial RuO₂ electrocatalysts (348 mV@10 mA/cm² and 80 mV/dec). Moreover, such electrocatalyst on nickel foam electrode also realizes superior OER durability to afford a current density of 70 mA/cm² at overpotential of only 300 mV for at least 28 h. The excellent electrocatalytic water oxidation activities of NiFe₂O₄-Pi can be attributed to the tuning electronic property and surface wettability by Pi ions functionalization. This work provides us a novel and effective approach to modify the photo-/electrocatalytic activity for transition metal oxides.     

Binary nickel ferrite oxide (NiFe2O4) nanoparticles coated on reduced graphene oxide as stable and high-performance asymmetric supercapacitor electrode material

Transition metal oxides are nowadays one of the most important materials in the manufacture of capacitive electrodes. The most important problems with these materials for applied energy storage devices are low specific energy and poor electrical conductivity. In this research nickel ferrite nanoparticles (NiFe₂O₄) and also hybrid of NiFe₂O₄/rGO are synthesized by hydrothermal method and characterized by XRD, Raman, and XPS analysis. The amount of porosity and specific surface area is studied by BET analysis as and surface morphology is studied by SEM and TEM. To investigate the effect of adding rGO to NiFe₂O₄ nanoparticles, from a hybrid electrode superconducting electrochemical tests are performed, including CV, EIS, and charge-discharge. This electrode with a capacitance of 584.63 F/g and capacitance retention of 91% after 2000 consecutive cycles can be a tempting option for supercapacitor applications.     

Hollow bimetallic M-Fe-P (M=Mn,Co, Cu) nanoparticles as efficient electrocatalysts for hydrogen evolution reaction

Searching for low-cost electrocatalysts with high activity towards the hydrogen evolution reaction (HER) is of great significance to enable large-scale hydrogen production via water electrolysis. In this study, by using inverse spinel MFe₂O₄(M = Mn, Fe, Co, Cu) nanoparticles (NPs) as the precursors, monodisperse bimetallic phosphide M-Fe-P NPs/C with hollow structures were readily obtained by a gas-solid annealing method. These hollow phosphide NPs displayed excellent HER activity in an acidic medium with a low loading amount of 0.2 mg cm⁻². In particular, the Co–Fe–P NPs/C shows highest HER activity that only requiring an overpotential of 97 mV to retain a current density of 10 mA cm⁻². A volcano relation between activity and incorporated elements was revealed. Incorporation of cation with high electronegativity stabilized the FeP active centres, while phase segregation resulted in the loss of activity for Cu–Fe–P NPs/C.     

Construction of dual Z-scheme NiO/NiFe2O4/Fe2O3 photocatalyst via incomplete solid state chemical combustion reactions for organic pollutant degradation with simultaneous hydrogen production

A dual Z-scheme NiO/NiFe₂O₄/Fe₂O₃ photocatalyst is prepared via incomplete solid state chemical combustion reaction of Ni(OH)₂ and Fe(OH)₃. The formed perfect interfaces between NiO and NiFe₂O₄ and between NiFe₂O₄ and Fe₂O₃ facilitate the transfers of photo-induced electrons. The photocatalytic degradation of methylene blue and simultaneous production of hydrogen was performed to evaluate the activity of the prepared samples. The dual Z-scheme NiO/NiFe₂O₄/Fe₂O₃ (600–2) photocatalyst obtained by heat treatment of Ni(OH)₂ and Fe(OH)₃ at 600 °C for 2.0 h shows an excellent photocatalytic performance. Additionally, the influences of simulated sunlight irradiation time and methylene blue concentration on the photocatalytic reactions are investigated. Besides, the reusability of sample is assessed via four cycle experiments. Further, a possible mechanism on the photocatalytic reaction is proposed. Maybe, this work would provide an ingenious idea for the construction of dual Z-scheme photocatalyst and the exploration for photocatalytic degradation of organic pollutants with simultaneous hydrogen production.     

Photocatalytic hydrogen evolution under visible light irradiation by the polyoxometalate α-[AlSiW11(H2O)O39] -Eosin Y system

It is important to construct a stable and efficient dye sensitization system for visible-light photocatalytic hydrogen evolution. Eosin Y (EY)-sensitized α-[AlSiW₁₁(H₂O)O₃₉]⁵⁻ (AlSiW₁₁) (an Al³⁺ substituted Keggin polyoxometalate (POM)) for the hydrogen evolution under visible light irradiation (λ > 420 nm) has been carried out in the presence of triethanolamine as electron donor and Pt as co-catalyst. EY can coordinate with AlSiW₁₁. The coordination association between AlSiW₁₁ and EY is beneficial to the charge transfer from EY to AlSiW₁₁ and to stability of EY. The system displays efficient and stable photocatalytic hydrogen evolution. The average apparent quantum efficiency and turnover number of EY during 20 h irradiation (λ > 420 nm) are 10.3% and 473, respectively. The highest quantum efficiency amounts to 28.0% under 520 nm monochromatic light irradiation. The present study highlights linking between dye and POM molecule as a way to develop new visible-light stable photocatalyst or system.     

Photocatalytic hydrogen evolution performance of metal ferrites /polypyrrole nanocomposites

The combination of inorganic (e.g., ferrite nanoparticles) and organic (e.g., conducting polymers) materials in the fabrication of heterojunctions or composites is an attractive scheme in the field of photocatalysis. We took the advantage of this phenomenon by fabricating MFerrite (M = Co, Ni, and Zn) @polypyrrole (MFerrite@Ppy) nanocomposites with a varying weight percentage of Ppy for the hydrogen production through photocatalytic water splitting under visible light irradiation. The structural, spectral, morphological, compositional, and optical features of the as-prepared nanocomposites were analyzed in full depth. The average crystallite sizes were estimated to be 30–40 nm from the XRD patterns which were further validated by TEM images from which a core-shell structure of the composites can be inferred. Likewise, the SEM images revealed spherical Ppy particles with a diameter in the range of 100–300 nm. From a photocatalytic viewpoint, CoFerrite@30Ppy is endowed with some peculiar characteristics including but not limited to strong light-harvesting ability (ranging between 300 and 650 nm), narrow optical band gap (as low as 1.6 eV), and higher photoluminescence (PL) lifetime (6.41 ns) which justify why it stands out among all composites in terms of photocatalysis. Under 8 h illumination of simulated visible light and using triethanolamine (TEOA) as a hole scavenger and Eosin-Y (EY) as a dye sensitizer, the photocatalytic hydrogen evolution (HER) amount for CoFerrite@30Ppy was found to be 10.44 mmol g^?1, far greater than any other composite catalysts in this study. From the PL spectra, it can be pointed out that sensitization of CoFerrite with 30 wt % Ppy conduces to simultaneous deceleration of the electron-hole recombination process and acceleration of the transference of excitons within the system.     

TmVO4/Fe2O3 nanocomposites: Sonochemical synthesis,characterization, and investigation of photocatalytic activity

Today, a unique method of treating environmental contaminants is drawing considerable attention. Organic dyes are significant wastes from myriad industries, including paper, food, and textiles, which have become a serious environmental concern and have the potential to be toxic to humans and living organisms. This study demonstrates the fabrication and characterization of thulium vanadate (TmVO₄) nanostructures and TmVO₄/Fe₂O₃ nanocomposites that were effectively applied in the photodecomposition efficiency of cationic and anionic organic contaminants. The TmVO₄/Fe₂O₃ nanocomposites were prepared through a sonochemical method, and triethylenetetramine (TETA) was employed as a precipitating and capping agent. The tests were performed using a probe as a sonication source (60 W, 18 kHz). The impact of TmVO₄ content (5, 10, 15, and 30%) on the modification of binary nanocomposites was studied in terms of morphological, optical, and photocatalytic properties. The recyclable magnetic TmVO₄/Fe₂O₃ nanocomposites with 15% TmVO₄ achieve 68.3% of eriochrome black t (EBT) utilizing visible origin. More notably, the binary TmVO₄/Fe₂O₃ nanocomposites reveal higher photocatalytic activity than the pure TmVO₄ and Fe₂O₃ nanoparticles.     

Porous sunflower plate-like NiFe2O4/CoNi–S heterostructure as efficient electrocatalyst for overall water splitting

Constructing high-efficient and nonprecious electrocatalysts is of primary importance for improving the efficiency of water splitting. Herein, a novel sunflower plate-like NiFe₂O₄/CoNi–S nanosheet heterostructure was fabricated via facile hydrothermal and electrodeposition methods. The as-fabricated NiFe₂O₄/CoNi–S heterostructure array exhibits remarkable bifunctional catalytic activity and stability toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in alkaline media. It presents a small overpotential of 219 mV and 149 mV for OER and HER, respectively, to produce a current density of 10 mA cm^?2. More significantly, when the obtained electrodes are used as both the cathode and anode in an electrolyzer, a voltage of 1.57 V is gained at 10 mA cm^?2, with superior stability for 72 h. Such outstanding properties are ascribed to: the 3D porous network structure, which exposes more active sites and accelerates mass transfer and gas bubble emission; the high conductivity of CoNi–S, which provides faster charge transport and thus promotes the electrocatalytic reaction of the composites; and the effective interface engineering between NiFe₂O₄ (excellent performance for OER) and CoNi–S (high activity for HER), which leads to a shorter transport pathway and thus expedites electron transfer. This work provides a new strategy for designing efficient and inexpensive electrocatalysts for water splitting.     

Dye-sensitized photocatalytic hydrogen evolution by using copper-based ternary refractory metal chalcogenides

The exploration of photocatalytic transformation of solar energy into H₂ through water splitting is an important direction towards sustainable and non-polluting energy in order to cover energy necessity partially. Ternary transition metal chalcogenides have been attracted attention among the other chalcogenides due to their potential applications in the photocatalytic and electrocatalytic hydrogen evolution. Herein, Cu₂WS₄ nanocubes and Cu₂WSe₄ nanosheets have been synthesized through a facile hot-injection method to benefit from the advantages such as minimizing the required pressure and reaction time by this technique. The photocatalytic hydrogen evolution activities of Cu₂WS₄ and Cu₂WSe₄ have been investigated under the visible light irradiation by using eosin-Y (EY) dye and triethanolamine (TEOA) as a photosensitizer and an electron donor, respectively. Cu₂WS₄ nanocubes have exhibited higher photocatalytic activity and stability than Cu₂WSe₄ nanosheets. The photocatalytic HER rates of Cu₂WS₄ and Cu₂WSe₄ have been determined as 1260 μmol g⁻¹ h⁻¹ and 861 μmol g⁻¹ h⁻¹, respectively. Photocatalytic HER activities were figured out in the order of Cu₂WS₄ > Cu₂WSe₄ which could be attributed to differences between proton reduction potential and the conduction band energy levels.     

Cobalt oxide on mesoporous carbon nitride for improved photocatalytic hydrogen production under visible light irradiation

Cobalt oxide (Co₃O₄) nanoparticles decorated on mesoporous carbon nitride (Co₃O₄/MCN) nanocomposites for photocatalytic hydrogen evolution were investigated in this work. MCN was prepared using 3-amino-1,2,4-triazole, high nitrogen content, as a single molecular carbon and nitrogen precursor and SiO₂ nanoparticles as the hard template. Complementary characterization techniques were employed to understand the textural and chemical properties of the nanocomposites. The bare MCN showed high photocatalytic activity under visible light irradiation without using any co-catalyst. The photocatalytic activity of Co₃O₄/MCN with a Co₃O₄ mass content of 5 wt % presented two times higher than the bare MCN, which is attributed to the enhanced visible-light harvesting and more efficient charge separation. Mechanistic study shows lower electron-hole recombination rate, higher charge separation efficiency occurs after the formation of p-n type heterojunction.     

Water splitting for hydrogen production with ferrites

The water splitting reaction by a thermo-chemical cycle using ferrites was investigated for H₂ production. In the first step (activation step), ferrites were thermally reduced at 1200 °C to form an oxygen-deficient ferrite. In the second step (water splitting step), the activated ferrites were oxidized by water at 800 °C to produce hydrogen. Among the prepared ferrites, Ni-ferrite was found to be the most suitable for H₂ production. NiFe₂O₄ produced an average of 0.442 cm³/g cycle of H₂. The H₂ productivity of the Ni-ferrite was much higher than that of the other ferrites at the same temperature. XRD showed that the crystal structure of NiFe₂O₄ during the redox reaction was not changed during the repeated cycles, indicating that NiFe₂O₄ was an excellent material in terms of structural stability and durability.     

Solar hydrogen production by two-step thermochemical cycles: Evaluation of the activity of commercial ferrites

In this work, we report on the evaluation of the activity of commercially available ferrites with different compositions, NiFe₂O₄, Ni_0.5Zn_0.5Fe₂O₄, ZnFe₂O₄, Cu_0.5Zn_0.5Fe₂O₄ and CuFe₂O₄, for hydrogen production by two-step thermochemical cycles, as a preliminary study for solar energy driven water splitting processes. The samples were acquired from Sigma–Aldrich, and are mainly composed of a spinel crystalline phase. The net hydrogen production after the first reduction–oxidation cycle decreases in the order NiFe₂O₄ > Ni_0.5Zn_0.5Fe₂O₄ > ZnFe₂O₄ > Cu_0.5Zn_0.5Fe₂O₄ > CuFe₂O₄, and so does the H₂/O₂ molar ratio, which is regarded as an indicator of potential cyclability. Considering these results, the nickel ferrite has been selected for longer term studies of thermochemical cycles. The results of four cycles with this ferrite show that the H₂/O₂ molar ratio of every two steps increases with the number of cycles, being the total amount stoichiometric regarding the water splitting reaction. The possible use of this nickel ferrite as a standard material for the comparison of results is proposed.     

Photocatalytic hydrogen evolution of nanoporous CoFe2O4 and NiFe2O4 for water splitting

The spinels CoFe₂O₄ and NiFe₂O₄ of nanoporous photocatalysts were prepared by dealloying and calcination. The photocatalytic performance for the hydrogen generation rate via water splitting was measured. The results revealed that CoFe₂O₄ exhibits a sheet-like nanoporous structure and that abundant mesopores are distributed in the nanosheets. NiFe₂O₄ shows a typical pore-ligament structure. The measurements show that hydrogen generation is exhibited by both oxides because the bandgap of CoFe₂O₄ and NiFe₂O₄ is higher than the water oxidization potential. The hydrogen generation rate is approximately 0.088 mmol h^?1g^?1 for CoFe₂O₄ and 0.026 mmol h^?1g^?1 for NiFe₂O₄ when the TEOA (10 vol%) sacrificial agent is adopted. This performance is significantly higher than that of methanol as the scavenger because TEOA increases the pH value of the solution, changes the negative shift in the conduction band energy level and improves the electron transport efficiency. The higher performance of CoFe₂O₄ is attributed to its larger specific surface area, ample unimpeded penetration diffusion paths and higher electron transfer rate.     

Spinel-type ferrite nanoparticles: Synthesis by the oil-in-water microemulsion reaction method and photocatalytic water-splitting evaluation

Cobalt, nickel and zinc nanosized spinel-type ferrites (MFe₂O₄, M: Co²⁺, Ni²⁺ and Zn²⁺) were synthesized by the novel oil-in-water microemulsion method. These compounds have not been fully studied for H₂ production by the water-splitting reaction, especially those prepared by microemulsion. Through proper characterization, features like crystal structure, efficient visible light absorption, high-sorption capacity and adequate textural properties, were demonstrated for thermal treated Co, Ni and Zn microemulsion synthesized nanoferrites. These characteristics favored the visible light-driven H₂ production (monitored by gas chromatography) of MFe₂O₄ nanoparticles dispersed in water (2% MeOH), under experimental conditions. Particularly, ZnFe₂O₄ yielded a higher amount of H₂ (354 μmolH₂g⁻¹) compared to Co (128 μmolH₂g⁻¹) and Ni (129 μmolH₂g⁻¹) ferrites in an 8 h experiment, presumably due to more favorable electronic band positions. This work represents a new contribution to the hydrogen evolution studies using ferrite nanoparticles.     

Synergistic effect of PANI and NiFe2O4 for photocatalytic hydrogen evolution under visible light

As an effective photocatalyst, PANI/NiFe₂O₄ nanocomposite was prepared by in situ polymerization of aniline. The physicochemical properties of the composite were characterized by TEM, XRD, FT-IR spectra, UV–vis spectroscopy, XPS and Photoelectrochemical Measurements. Compared with NiFe₂O₄ and PANI, PANI/NiFe₂O₄ nanocomposite has a better photocatalytic activity, which exhibited the remarkable property of hydrogen production under visible light. The photocatalytic mechanism was also discussed. The heterojunction of PANI and NiFe₂O₄ promoted the separation of photogenerated e^? and h⁺ on the surface of PANI/NiFe₂O₄. Besides, the structure of PANI/NiFe₂O₄ in the polymerization was detected by FT-IR. NiFe₂O₄ was proved that in favor of the formation of nucleate phenazine-like structure in the progress of in situ polymerization. Then the chain structure of conductive PANI was formed, which leading to the promotion of photocatalytic activity.