Next Article in Journal
Charging the Future with Pioneering MXenes: Scalable 2D Materials for Next-Generation Batteries
Previous Article in Journal
Eco-Friendly Synthesis of Silver Nanoparticles from Ligustrum ovalifolium Flower and Their Catalytic Applications
Previous Article in Special Issue
Highly Sensitive and Selective SnO2-Gr Sensor Photoactivated for Detection of Low NO2 Concentrations at Room Temperature
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Nanomaterials
Volume 15
Issue 14
10.3390/nano15141088
nanomaterials-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

High-Sensitivity, Low Detection Limit, and Fast Ammonia Detection of Ag-NiFe2O4 Nanocomposite and DFT Study

by
Xianfeng Hao
,
Yuehang Sun
,
Zongwei Liu
,
Gongao Jiao
and
Dongzhi Zhang
*
College of Control Science and Engineering, China University of Petroleum (East China), Qingdao 266580, China
*
Author to whom correspondence should be addressed.
Nanomaterials 2025, 15(14), 1088; https://doi.org/10.3390/nano15141088
Submission received: 30 May 2025 / Revised: 27 June 2025 / Accepted: 1 July 2025 / Published: 14 July 2025
(This article belongs to the Special Issue Advanced Nanomaterials in Gas and Humidity Sensors: Second Edition)
Browse Figures
Versions Notes

Abstract

Ammonia (NH3) is one of the characteristic gases used to detect food spoilage. In this study, the 10 wt% Ag-NiFe2O4 nanocomposite was synthesized via the hydrothermal method. Characterization results from SEM, XRD, and XPS analyzed the microstructure, elemental composition, and crystal lattice features of the composite, confirming its successful fabrication. Under the optimal working temperature of 280 °C, the composite exhibited excellent gas-sensing properties towards NH3. The 10 wt% Ag-NiFe2O4 sensor demonstrates rapid response and recovery, as well as high sensitivity, towards 30 ppm NH3, with response and recovery times of merely 3 s and 9 s, respectively, and a response value of 4.59. The detection limit is as low as 0.1 ppm, meeting the standards for food safety detection. Additionally, the sensor exhibits good short-term repeatability and long-term stability. Additionally, density functional theory (DFT) simulations were conducted to investigate the gas-sensing advantages of the Ag-NiFe2O4 composite by analyzing the electron density and density of states, thereby providing theoretical guidance for experimental testing. This study facilitates the rapid detection of food spoilage and promotes the development of portable food safety detection devices.

1. Introduction

NH3 is a colorless gas with a pungent odor, widely present in nature and industrial production [1]. In the field of fish storage and preservation, the generation and accumulation of ammonia are directly related to the spoilage process of fish, as ammonia is one of the final products of protein decomposition [2,3,4]. Changes in ammonia concentration are commonly used as a key indicator to assess the freshness of fish. After fish die, the proteins and other nitrogen-containing compounds in their bodies begin to decompose [5]. This process is primarily driven by microorganisms such as bacteria and fungi, which break down the proteins in the fish tissue into amino acids, and further decompose the amino acids into ammonia, hydrogen sulfide, and other volatile compounds. Therefore, timely and accurate detection of ammonia produced during the spoilage process of fish provides data support for accurately assessing fish freshness and optimizing storage conditions.
Commonly used toxin detection sensors include optical sensors [6], colorimetric sensors [7], electrochemical sensors [8], and semiconductor sensors [9]. Among these, metal oxide semiconductor gas sensors have garnered extensive attention due to their low cost, high sensitivity, and rapid response and recovery characteristics [10]. NiFe2O4 is a spinel-structured composite oxide and is one of the research hotspots in the field of gas-sensing due to its high sensitivity, low cost, and good thermal stability [11,12,13,14,15,16]. Rezaeipour et al. [17] prepared porous nickel ferrite nanoparticles using a hydrothermal method. The sensor employs a side-heating structure, with a glass plate adhered to the heating element to fabricate a low-cost sensing component. This configuration allows for the evaluation of the sensor’s acetone-sensing characteristics at various operating temperatures. The selectivity of the sensor was tested towards multiple gases, including methanol, xylene, dichloromethane, and toluene. At an operating temperature of 190 °C, the sensor exhibited a high response value of 78% towards 100 ppm acetone and a response value of 67% towards ethanol. The sensor exhibits satisfactory stability and repeatability, and it can swiftly respond to acetone within 30 s. In a related study, Zhang et al. [18] fabricated NiFe bimetallic organic framework (MOF) octahedra using a straightforward reflux technique and then transformed them into NiFe2O4 nanooctahedra through calcination. The synergistic presence of phthalic acid (PTA) and 3,3-diaminobiphenyl (DAB) promoted the creation of NiFe bimetallic MOF octahedra. Following a thermal treatment, the NiFe2O4 nanoparticles (30 nm) experienced an approximate 85% weight loss, evolving into porous nano-octahedra with a hollow interior. Utilizing these NiFe2O4 nano-octahedra, a sensor was developed that exhibited remarkable toluene gas-sensing capabilities, characterized by notable long-term stability over 30 days, swift response, and brief recovery times (25 s/40 s), along with a low detection threshold of 1 ppm at 260 °C. Among all the strategies, noble metal doping is undoubtedly a highly appealing approach, which can be attributed to the chemical and electronic sensitization behaviors of noble metals [19]. Owing to their unique catalytic mechanisms, noble metals can significantly reduce the adsorption activation energy on the surface of the doped materials, thereby enhancing the sensitivity, response, and selectivity of the sensors [20].
In this investigation, Ag-NiFe2O4 nanocomposites were synthesized employing a hydrothermal synthesis approach. Various characterization techniques, including SEM, XPS, and XRD, were employed to analyze the composites, confirming the successful synthesis of Ag-NiFe2O4. The gas-sensing capabilities of the sensors were evaluated, revealing that the sensor doped with 10 wt% Ag-NiFe2O4 exhibited the highest response at 280 °C. Additionally, corroborated by DFT calculations, simulations authenticated the enhanced ammonia adsorption mechanism of the Ag-NiFe2O4 composite.

2. Experimental

2.1. Materials

The anhydrous ethanol (C2H6O, 99.7%) and polyvinylpyrrolidone (PVP, average molecular weight of 1,300,000) used were from Maclin Biochemical Co., Ltd. (Shanghai, China). The producer of silver nitrate (Ag(NO3)2, 99.8%) is Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Nickel nitrate hexahydrate (Ni(NO3)2·6H2O, 98%), ferric nitrate nonahydrate (Fe(NO3)3·9H2O, 98.5%), sodium hydroxide (NaOH, 99%), and sodium borohydride (NaBH4, 99%) were from Shanghai Hushi Laboratory Equipment Co., Ltd. (Shanghai, China). Sodium citrate (C6H5O7Na3, 98%) is produced by Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China).

2.2. Synthesis of Ag-NiFe2O4 Nanocomposites

Add 0.1308 g of Ni(NO3)2·6H2O and 0.3636 g of Fe(NO3)3·9H2O to 40 mL of deionized water while stirring continuously. Stir on a magnetic stirrer until a transparent solution is formed, then gradually add 1 mol/L NaOH solution dropwise until the pH of the solution reaches 12. Stir for 3 h. After stirring, transfer the mixture into a hydrothermal reactor and heated at 180 °C for 18 h. Subsequently, collect the precipitate and wash it multiple times to remove impurities, then dry it in an oven at 60 °C for 24 h to obtain NiFe2O4 nanoparticles.
Add 1 mL of 10 mol/L Ag(NO3)2 solution to a beaker, followed by the addition of 1 mL of 1 mol/L PVP. Agitate the mixture within an ice-water bath for a duration of 1 h, then add 1.5 mL of 10 mol/L C6H5NaO7 solution and stir for another hour. While stirring in the ice-water bath, gradually add 0.16 mL of 0.1 mol/L NaBH4 solution dropwise. After the reaction is complete, collect the precipitate and wash it multiple times to remove impurities, then dry it to obtain silver nanoparticles.
In the synthesis of Ag-NiFe2O4 composites, 0.3 g of NiFe2O4 particulate matter was dispersed in 10 mL of anhydrous ethanol. Based on the mass of NiFe2O4 and mass ratios of 5 wt%, 10 wt%, and 15 wt%, 0.015 g, 0.030 g, and 0.045 g of silver nanoparticles were added to the three respective NiFe2O4 suspensions. After ultrasonic treatment, the mixtures were stirred at 60 °C for 12 h. The synthesized composites with varying silver nanoparticle loadings were, respectively, defined as 5 wt% Ag-NiFe2O4, 10 wt% Ag-NiFe2O4, and 15 wt% Ag-NiFe2O4.

3. Results and Discussion

3.1. Characterization of the Prepared Material

The XRD pattern of Ag-NiFe2O4 is shown in Figure 1a. The diffraction peaks of NiFe2O4 are concentrated at 2θ = 30.294°, 35.685°, 37.329°, 43.373°, 53.819°, 57.375°, 63.013°, 71.504°, 74.572°, 75.584°, and 79.591°, corresponding to the (2 2 0), (3 1 1), (2 2 2), (4 0 0), (4 2 2), (5 1 1), (4 4 0), (6 2 0), (5 3 3), (6 2 2), and (4 4 4) crystal planes (JCPDS 74-2081). The diffraction peaks of Ag are located at 2θ = 38.200°, 44.400°, 64.600°, 77.597°, and 81.755°, corresponding to the (1 1 1), (2 0 0), (2 2 0), (3 1 1), and (2 2 2) crystal planes (JCPDS 87-0720). This indicates the successful preparation of Ag-NiFe2O4. The SEM image of Ag-NiFe2O4 is shown in Figure 1b. Ag-NiFe2O4 appears in the form of nanoparticles. The average particle size of the nanoparticles is 100–200 nm. The material exhibits good crystallinity and a uniform nanostructure. The larger specific surface area provides a foundation for the preparation of high-performance gas sensors.
The elemental composition of the 10 wt% Ag-NiFe2O4 nanocomposite was characterized using X-ray photoelectron spectroscopy (XPS, Thermo Fisher Scientific, Waltham, MA, USA). The XPS analysis curve of the 10 wt% Ag-NiFe2O4 sample is shown in Figure 2. As illustrated in Figure 2a, the full spectrum of the 10 wt% Ag-NiFe2O4 sample confirms the presence of Ag, Ni, and Fe elements in the composite. In the Ag 3d spectrum, the two peaks at 370.63 eV and 376.68 eV correspond to the Ag 3d5/2 and Ag 3d3/2 orbitals, indicating the presence of metallic Ag (Figure 2b). In the Ni 2p spectrum, the characteristic peaks at 856.75 eV and 847.33 eV correspond to Ni 2p3/2 and Ni 2p1/2 orbitals, respectively (Figure 2c). In addition to the main peaks, satellite peaks were also observed. These satellite peaks, which typically appear on the higher binding energy side of the main peaks, are characteristic of Ni2+. Their presence further confirms that the oxidation state of Ni is +2. As shown in Figure 2d, the Fe 2p spectrum displays two main peaks, with characteristic peaks at 712.42 eV and 725.88 eV corresponding to Fe 2p3/2 and Fe 2p1/2 orbitals, respectively. Satellite peaks were also observed, confirming that the oxidation state of Fe is +3.

3.2. NH3 Sensitive Properties

The gas sensitivity performance tests of NiFe2O4, 5 wt% Ag-NiFe2O4, 10 wt% Ag-NiFe2O4 and 15 wt% Ag-NiFe2O4 thin-film gas sensors are shown in Figure 3. The test results of pure NiFe2O4, 5 wt% Ag-NiFe2O4, 10 wt% Ag-NiFe2O4, and 15 wt% Ag-NiFe2O4 sensors for 50 ppm NH3 gas at different temperatures are shown in Figure 3a. Compared to the other sensors, the 10 wt% Ag-NiFe2O4 sensor exhibits the highest response. Additionally, the response at 280 °C is higher than at other temperatures, indicating that the optimal operating temperature is 280 °C. The fitted curves of the NiFe2O4, 5 wt% Ag-NiFe2O4, 10 wt% Ag-NiFe2O4, and 15 wt% Ag-NiFe2O4 sensors at 280 °C are shown in Figure 3b. The response curves of the 10 wt% Ag-NiFe2O4 sensor to NH3 (0.1, 0.3, 0.5, 1, 3, 5, 10, 30, 50, and 100 ppm) are shown in Figure 3c, with responses of 1.72, 1.89, 2.02, 2.21, 2.51, 3.06, 3.24, 4.59, 5.36, and 6.14. Figure 3d illustrates the response/recovery times of the NiFe2O4, 5 wt% Ag-NiFe2O4, 10 wt% Ag-NiFe2O4, and 15 wt% Ag-NiFe2O4 sensors, which are 2 s/19 s, 2 s/12 s, 3 s/9 s, and 6 s/17 s, respectively. The 10 wt% Ag-NiFe2O4 sensor exhibits exceptional response and recovery characteristics.
The selectivity of the 10 wt% Ag-NiFe2O4 sensor was investigated. As illustrated in Figure 4a, the selectivity curves of the sensor were tested under different gas atmospheres at a concentration of 50 ppm. Compared to the response values for NH3 gas, the sensor exhibits lower response values for other gases, indicating good selectivity of the 10 wt% Ag-NiFe2O4 sensor. This can be attributed to the catalytic effect of the noble metal Ag and the differences in the reactivity of gas molecules at different temperatures. Furthermore, the 10 wt% Ag-NiFe2O4 sensor demonstrates good repeatability for NH3 gas (Figure 4b). Figure 4c presents the long-term stability test curve of the sensor over a period of 30 days. During the testing period, the sensor was placed in a constant temperature and humidity chamber, and a working voltage stress was continuously applied to ensure that the sensor remained in an operational state and a relatively stable experimental environment, during which the sensor demonstrated excellent long-term stability. Table 1 provides a comparison of gas-sensing parameters for various ammonia sensors reported in recent years. This sensor has the advantage of fast response/recovery speeds, which will make ammonia detection quicker and more efficient.

3.3. NH3 Sensitive Mechanism

The sensitivity performance of Ag-NiFe2O4 nanocomposites to NH3 gas can be explained through the oxygen adsorption model. In this work, the sensor is placed in the air with an operating temperature of 280 °C. The O2 molecules in the air will adsorb to form O−, as shown in Equations (1)–(3).
O2 (gas) → O2 (ads)
O2 (ads) + e− → O2− (ads)
O2− (ads) + e− → 2O− (ads)
The resistance change in the Ag-NiFe2O4 nanocomposite upon NH3 adsorption is attributed to the variation in the form of adsorbed oxygen (O−) on the material surface. The formation of a Schottky junction between Ag and NiFe2O4, due to the difference in their work functions, leads to the accumulation of a depletion layer. This results in an increased number of oxygen adsorption sites on the surface of the composite. The catalytic effect of the noble metal Ag also promotes the reaction between NH3 and the adsorbed oxygen, thereby enhancing the sensitivity of the composite to a NH3. However, as the proportion of Ag increases, the oxygen adsorption sites on the composite surface are occupied by metallic Ag. Excessive Ag content is detrimental to the formation of surface-adsorbed oxygen, thereby weakening the composite’s response to the target gas. Figure 5 shows the mechanism model of NH3 gas adsorption on Ag-NiFe2O4 nanocomposites. Since NiFe2O4 is a p-type semiconductor, holes are its carriers [27]. When the sensor is in an air atmosphere, free electrons transfer from the lower Fermi level of Ag to the higher Fermi level of NiFe2O4, forming an electron depletion layer. Ambient oxygen molecules capture electrons from the surface of the composite material to form O−. Additionally, due to the oxygen spillover effect of the noble metal, Ag catalyzes the generation of more O−. When the sensor is exposed to NH3 gas, NH3 molecules react with the adsorbed O− on the material surface [28,29]. The response mechanism of the above process is shown in Figure 5. The reaction between ammonia and adsorbed oxygen on the surface of the composite material is shown in Equation 4:
2NH3 (ads) + 3O− (ads) → 2N2 + 3H2O + 3e−

3.4. DFT Calculation

Based on the XRD characterization results, the crystallographic lattice parameters of the simulation model were determined. First-principle simulations were then performed to calculate the ammonia-adsorption model of the Ag-NiFe2O4 composite. Structural optimization and energy calculations were carried out for the composite model. Figure 6a,b show the charge density diagrams of Ag-NiFe2O4 after adsorption of Ag-NiFe2O4 and NH3. The increase and decrease in charge density are represented by the red and blue regions, respectively [30]. As shown in Figure 6c, in comparison to the total density of states (TDOS) of NiFe2O4, the peaks of Ag-NiFe2O4 between −20 eV and −3 eV shift to the right, while the peaks between −3 eV and −2.5 eV move slightly to the left. The partial density of states (PDOS) of Ag-NiFe2O4 is shown in Figure 6d. The rightward shift and weakening of the peak in the range of −20 eV to −17.5 eV is attributed to the O 2s orbital. The peak state density changes significantly within the range of −10 eV to −5 eV, indicating that the electronic state distribution of the material changes after Ag composite, and electron transfer occurs in the composite material. The left shift in the peak within the range of −3 eV to −2.5 eV is affected by Fe 3d and Ag 5d. The TDOS of the Ag-NiFe2O4 system before and after the adsorption of NH3 is shown in Figure 6e,f. After the adsorption of NH3 gas, a new peak appears at −17.5 eV, which is generated by the interaction of the H 1s and N 2s orbitals, and a new peak appears at −8 eV, which is generated by the interaction of the H 1s and N 2p orbitals. The peak increase within the range of −7 eV to −4 eV is caused by the N 2p orbitals in NH3, and the peak left shift at −2 eV is produced by the combined action of Ni 3d, N 2p, and O 2p orbitals.

4. Conclusions

In this study, the 10 wt% Ag-NiFe2O4 material was synthesized via the hydrothermal method. The Ag-NiFe2O4 composite was characterized by XRD, SEM, and XPS, and an NH3 sensor was fabricated based on this material. At 280 °C, the response of 10 wt% Ag-NiFe2O4 to 30 ppm NH3 was 4.59, with good response and recovery times of 3 s and 9 s, respectively. Among various other gaseous environments, the sensor exhibited the highest response to NH3, indicating its superior selectivity. Additionally, the sensor also demonstrates satisfactory repeatability. The sensitivity mechanism towards NH3 was further elucidated through first-principles calculations, thereby providing theoretical support for the experimental testing of the Ag-NiFe2O4 material.

Author Contributions

Conceptualization, Y.S.; Methodology, D.Z.; Software, Y.S.; Validation, G.J.; Formal analysis, X.H. and Z.L.; Investigation, Z.L. and G.J.; Resources, D.Z.; Data curation, X.H.; Writing—original draft, X.H. and Y.S.; Writing—review & editing, D.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the Fundamental Research Funds for the Central Universities (24CX02014A).

Data Availability Statement

The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Hou, J.F.; Liu, X.N.; Sun, H.Y.; He, Y.; Qiao, S.D.; Zhang, C.; Zhao, W.J.; Ma, Y.F. Deep learning based light-induced thermoelastic spectroscopy signal separation for hybrid gas sensing. Sens. Actuators B Chem. 2025, 440, 137918. [Google Scholar] [CrossRef]
  2. Lv, W.; Yang, J.H.; Xu, Q.D.; Mehrez, J.A.A.; Shi, J.; Quan, W.J.; Luo, H.Y.; Zeng, M.; Hu, N.T.; Wang, T.; et al. Wide-range and high-accuracy wireless sensor with self-humidity compensation for real-time ammonia monitoring. Nat. Commun. 2024, 15, 6936. [Google Scholar] [CrossRef] [PubMed]
  3. Luo, L.X.; Hou, L.X.; Cui, X.P.; Zhan, P.X.; He, P.; Dai, C.Y.; Li, R.A.; Dong, J.C.; Zou, Y.; Liu, G.M.; et al. Self-condensation-assisted chemical vapour deposition growth of atomically two-dimensional MOF single-crystals. Nat. Commun. 2024, 15, 3618. [Google Scholar] [CrossRef]
  4. Anasori, B.; Lukatskaya, M.R.; Gogotsi, Y. 2D metal carbides and nitrides (MXenes) for energy storage. Nat. Rev. Mater. 2017, 2, 16098. [Google Scholar] [CrossRef]
  5. Nam, G.B.; Ryu, J.E.; Eom, T.H.; Kim, S.J.; Suh, J.M.; Lee, S.; Choi, S.; Moon, C.W.; Park, S.J.; Lee, S.M.; et al. Real-time tunable gas sensing platform based on SnO2 nanoparticles activated by blue micro-light-emitting diodes. Nano-Micro Lett. 2024, 16, 261. [Google Scholar] [CrossRef] [PubMed]
  6. Mulimani, P.; Bhat, M.P.; Patil, P.; Aralekallu, S.; Kapavarapu, R.; Yu, J.; Kurkuri, M.; Kalkhambkar, R.G. Colorimetric devices for naked-eye detection of Fe3+ and Cu2+: Optical properties, DFT calculations, and molecular docking studies. J. Water Process. Eng. 2024, 59, 105030. [Google Scholar] [CrossRef]
  7. Gong, H.; Pang, T.; Yang, X.; Chen, F.; Jiang, N.; Li, Y.; Chen, C.; Cai, C. Rapid visual detection of tobacco mosaic virus using a portable paper-based molecularly imprinted sensor. Sens. Actuators B Chem. 2025, 424, 136909. [Google Scholar] [CrossRef]
  8. Liang, Q.; Zhou, D.; Zhang, K.; Camarada, M.B.; Xiong, J.; Liao, X. A novel portable electrochemical sensor based on post-synthetic modified Cu-MOF for highly sensitive electrochemical detection of pefloxacin in food samples. Microchem. J. 2025, 209, 112895. [Google Scholar] [CrossRef]
  9. Wang, D.Y.; Zhang, D.; Yang, Y.; Mi, Q.; Zhang, J.H.; Yu, L.D. Multifunctional latex/polytetrafluoroethylene-based triboelectric nanogenerator for self-powered organ-like MXene/metal-organic framework-derived CuO nanohybrid ammonia sensor. ACS Nano 2025, 15, 2911–2919. [Google Scholar] [CrossRef]
  10. Tie, Y.; Ma, S.Y.; Pei, S.T.; Zhang, Q.X.; Zhu, K.M.; Zhang, R.; Xu, X.H.; Han, T.; Liu, W.W. Pr doped BiFeO3 hollow nanofibers via electrospinning method as a formaldehyde sensor. Sens. Actuator B Chem. 2020, 308, 127689. [Google Scholar] [CrossRef]
  11. Wang, B.B.; Xing, Y.L.; Zhang, K.W.; Wang, Z.; Xia, Y.Z.; Long, X.J. Electron-deficient organic molecules based on B←N unit: A N-type room-temperature chemiresistive sensors with moisture resistance. Adv. Sci. 2024, 11, 2409890. [Google Scholar] [CrossRef]
  12. Pflüger, T.; Gschell, M.; Zhang, L.; Shnitsar, V.; Zabadné, A.J.; Zierep, P.; Günther, S.; Einsle, O.; Andrade, S.L.A. How sensor Amt-like proteins integrate ammonium signals. Sci. Adv. 2024, 10, eadm9441. [Google Scholar] [CrossRef]
  13. Fu, F.M.; Zhang, X.Y.; Wang, W.; Xie, X.J. Colorimetric optode sensor with tripodal ionophore for rapid urinary ammonium determination. ACS Sens. 2025, 10, 3757–3762. [Google Scholar] [CrossRef] [PubMed]
  14. Chang, Z.Q.; Fuh, H.R.; Bau, J.Y.; Cho, J.; Abid, M.; Bae, T.S.; Chung, H.S.; Coileáin, C.Ó.; Chang, C.R.; Wu, H.C. Impact of molecule-molecule interactions when discerning low-concentration hazardous gas mixtures. ACS Nano 2025, 19, 7202–7212. [Google Scholar] [CrossRef] [PubMed]
  15. Bhagat, B.; Gupta, S.K.; Mandal, D.; Gor, A.A.; Bandyopadhyay, R.; Mukherjee, K. Probing the p-type chemiresistive response of NiFe2O4 nanoparticles for potential utilization as ethanol sensor. Chem. Asian J. 2024, 19, e202300841. [Google Scholar] [CrossRef] [PubMed]
  16. Zhang, H.; Zhang, X.X.; Qiu, C.K.; Jia, P.L.; An, F.; Zhou, L.N.; Zhu, L.; Zhang, D.Z. Polyaniline/ZnO heterostructure-based ammonia sensor self-powered by electrospinning of PTFE-PVDF/MXene piezo-tribo hybrid nanogenerator. Chem. Eng. J. 2024, 496, 154226. [Google Scholar] [CrossRef]
  17. Rezaeipour, A.; Dehghani, S.; Hoghoghifard, S. Acetone sensor based on porous nickel ferrite nanoparticles. J. Mater. Sci. Mater. Electron. 2022, 33, 26276–26285. [Google Scholar] [CrossRef]
  18. Zhang, Y.L.; Jia, C.W.; Wang, Q.Y.; Kong, Q.; Chen, G.; Guan, H.T.; Dong, C.J. MOFs-derived porous NiFe2O4 nano-octahedrons with hollow interiors for an excellent toluene gas sensor. Nanomaterials 2019, 9, 1059. [Google Scholar] [CrossRef]
  19. Shao, X.; Zhang, D.; Tang, M.; Zhang, H.; Wang, Z.; Jia, P.; Zhai, J. Amorphous Ag catalytic layer-SnO2 sensitive layer-graphite carbon nitride electron supply layer synergy-enhanced hydrogen gas sensor. Chem. Eng. J. 2024, 495, 153676. [Google Scholar] [CrossRef]
  20. Tang, M.X.; Qin, C.; Sun, X.Y.; Li, M.W.; Wang, Y.H.; Cao, J.L.; Wang, Y. Enhanced H2 gas sensing performances by Pd-loaded In2O3 microspheres. Appl. Phys. A 2024, 130, 741. [Google Scholar] [CrossRef]
  21. Praveen, L.L.; Singh, N.P.; Vardhan, R.V.; Mandal, S. All-printed WO3 films on an Ag-interdigitated electrode derived from aqueous screen-printable inks for room-temperature ammonia gas detection. Flex. Print. Electron. 2025, 10, 015008. [Google Scholar] [CrossRef]
  22. Chao, J.F.; Liu, Z.D.; Xing, S.M.; Gao, Q.Q.; Zhao, J.Z. Enhanced ammonia detection of gas sensors based on square-like tungsten oxide loaded by Pt nanoparticles. Sens. Actuators B Chem. 2021, 347, 130621. [Google Scholar] [CrossRef]
  23. Zhai, H.C.; Wu, Z.Y.; Xiao, K.; Ge, M.Y.; Liu, C.X.; Tian, P.F.; Wan, J.; Wang, J.L.; Kang, J.Y.; Chu, J.H.; et al. p-Type β-Ga2O3 film room-temperature NH3 gas sensors with fast gas sensing and a low limit of detection. J. Mater. Chem. C 2024, 12, 19526–19535. [Google Scholar] [CrossRef]
  24. Karmakar, S.; Sett, A.; Maity, P.C.; Karmakar, G.; Sha, R.; Bhattacharyya, T.K.; Lahiri, I. A room-temperature gas sensor based on 2D Ni-Co-Zn ternary oxide nanoflakes for selective and sensitive ammonia detection. Dalton Trans. 2023, 52, 16500–16512. [Google Scholar] [CrossRef]
  25. Haridas, V.; Sukhananazerin, A.; Sneha, J.M.; Pullithadathil, B.; Narayanan, B. α-Fe2O3 loaded less-defective graphene sheets as chemiresistive gas sensor for selective sensing of NH3. Appl. Surf. Sci. 2020, 517, 146158. [Google Scholar] [CrossRef]
  26. Punetha, D.; Pandey, S.K. Enhancement and optimization in sensing characteristics of ammonia gas sensor based on light assisted nanostructured WO3 thin film. IEEE Sens. J. 2020, 20, 14617–14623. [Google Scholar] [CrossRef]
  27. Qian, X.J.; Chen, Y.P.; Tao, Y.Y.; Zhang, J.; Zhang, G.F.; Xu, H.Y. Facile synthesis of NiFe2O4-based nanoblocks for low-temperature detection of trace n-butanol. RSC Adv. 2024, 14, 2214–2225. [Google Scholar] [CrossRef]
  28. Xia, Y.D.; Dai, J.H.; Cao, Y.R.; Ni, Y.X.; Ou, K.; Wang, H.Y. High-performance room temperature NH3 sensor based on zigzag morphology TiO2/Fe2O3 heterojunction. Eur. Phys. J. Plus 2025, 140, 138. [Google Scholar] [CrossRef]
  29. Alagarasan, D.; Hegde, S.S.; Naik, R.; Shetty, H.D.; Prasad, H.B.S.; Alshahrani, T.; AlFaify, S.; Shkir, M. Remarkable NH3 gas sensing performance of spray deposited Tb doped WO3 thin films at room temperature. J. Photoch. Photobio. A Chem. 2024, 459, 116087. [Google Scholar] [CrossRef]
  30. Zhang, D.; Yu, S.J.; Wang, X.W.; Huang, J.K.; Pan, W.J.; Zhang, J.H.; Meteku, B.E.; Zeng, J.B. UV illumination-enhanced ultrasensitive ammonia gas sensor based on (001)TiO2/MXene heterostructure for food spoilage detection. J. Hazard. Mater. 2021, 423, 127160. [Google Scholar] [CrossRef]
Nanomaterials 15 01088 g001
Figure 1. (a) XRD and (b) SEM of 10 wt% Ag-NiFe2O4-samples.
Figure 1. (a) XRD and (b) SEM of 10 wt% Ag-NiFe2O4-samples.
Nanomaterials 15 01088 g001
Nanomaterials 15 01088 g002
Figure 2. The XPS plot of Ag-NiFe2O4 sample: (a) full spectrum scanning, (b) Ag 3d, (c) Ni 2p, (d) Fe 2p.
Figure 2. The XPS plot of Ag-NiFe2O4 sample: (a) full spectrum scanning, (b) Ag 3d, (c) Ni 2p, (d) Fe 2p.
Nanomaterials 15 01088 g002
Nanomaterials 15 01088 g003
Figure 3. (a) Response values of Ag-NiFe2O4 sensor with different mass ratios to 50 ppm NH3 at different temperatures. (b) Fitted curves of responses to different concentrations of NH3 at 280 °C. (c) Response to 0.1–100 ppm NH3 at 280 °C. (d) The response-recovery time to 30 ppm NH3 at 280 °C.
Figure 3. (a) Response values of Ag-NiFe2O4 sensor with different mass ratios to 50 ppm NH3 at different temperatures. (b) Fitted curves of responses to different concentrations of NH3 at 280 °C. (c) Response to 0.1–100 ppm NH3 at 280 °C. (d) The response-recovery time to 30 ppm NH3 at 280 °C.
Nanomaterials 15 01088 g003
Nanomaterials 15 01088 g004
Figure 4. (a) Selectivity of 10 wt% Ag-NiFe2O4 sensor to 50 ppm different gases at 280 °C. (b) Repeatability of 10 wt% Ag-NiFe2O4 sensor at 0.5 ppm, 5 ppm, 50 ppm concentration NH3. (c) The 30-day long-term stability of the 10 wt% Ag-NiFe2O4 sensor in response to 0.5 ppm, 5 ppm, 50 ppm of NH3.
Figure 4. (a) Selectivity of 10 wt% Ag-NiFe2O4 sensor to 50 ppm different gases at 280 °C. (b) Repeatability of 10 wt% Ag-NiFe2O4 sensor at 0.5 ppm, 5 ppm, 50 ppm concentration NH3. (c) The 30-day long-term stability of the 10 wt% Ag-NiFe2O4 sensor in response to 0.5 ppm, 5 ppm, 50 ppm of NH3.
Nanomaterials 15 01088 g004
Nanomaterials 15 01088 g005
Figure 5. Sensitivity mechanism of Ag-NiFe2O4 in air and sensitivity mechanism of Ag-NiFe2O4 in NH3 gas.
Figure 5. Sensitivity mechanism of Ag-NiFe2O4 in air and sensitivity mechanism of Ag-NiFe2O4 in NH3 gas.
Nanomaterials 15 01088 g005
Nanomaterials 15 01088 g006
Figure 6. Charge density diagram of (a) Ag-NiFe2O4 and (b) Ag-NiFe2O4 after adsorption of NH3. (c) The total state density of NiFe2O4 and Ag-NiFe2O4. (d) Projection state density of Ag-NiFe2O4. (e) The total state density of Ag-NiFe2O4 before and after NH3 adsorption. (f) Projected state density after Ag-NiFe2O4 adsorption of NH3.
Figure 6. Charge density diagram of (a) Ag-NiFe2O4 and (b) Ag-NiFe2O4 after adsorption of NH3. (c) The total state density of NiFe2O4 and Ag-NiFe2O4. (d) Projection state density of Ag-NiFe2O4. (e) The total state density of Ag-NiFe2O4 before and after NH3 adsorption. (f) Projected state density after Ag-NiFe2O4 adsorption of NH3.
Nanomaterials 15 01088 g006
Table 1. Comparison of the NH3 sensing performances of gas sensors.
Table 1. Comparison of the NH3 sensing performances of gas sensors.
Sensing MaterialsTemp. (°C)Conc. (ppm)ResponseRes./Rec. Time (s)Ref.
WO3 porous nanoplatesRT100~34090 s/30 s[21]
1%Pt/WO3270 °C100∼107 s/7 s[22]
β-Ga2O3RT50219.1%42.3 s/60 s[23]
NiCo2ZnO4RT2522.6974.84 s/240 s[24]
α-Fe2O4/graphene250 °C1013.5%648 s/152 s[25]
WO3 thin film250 °C5012.5813 s/34 s[26]
10 wt% Ag-NiFe2O4280 °C304.593 s/9 sThis work
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Hao, X.; Sun, Y.; Liu, Z.; Jiao, G.; Zhang, D. High-Sensitivity, Low Detection Limit, and Fast Ammonia Detection of Ag-NiFe2O4 Nanocomposite and DFT Study. Nanomaterials 2025, 15, 1088. https://doi.org/10.3390/nano15141088

AMA Style

Hao X, Sun Y, Liu Z, Jiao G, Zhang D. High-Sensitivity, Low Detection Limit, and Fast Ammonia Detection of Ag-NiFe2O4 Nanocomposite and DFT Study. Nanomaterials. 2025; 15(14):1088. https://doi.org/10.3390/nano15141088

Chicago/Turabian Style

Hao, Xianfeng, Yuehang Sun, Zongwei Liu, Gongao Jiao, and Dongzhi Zhang. 2025. "High-Sensitivity, Low Detection Limit, and Fast Ammonia Detection of Ag-NiFe2O4 Nanocomposite and DFT Study" Nanomaterials 15, no. 14: 1088. https://doi.org/10.3390/nano15141088

APA Style

Hao, X., Sun, Y., Liu, Z., Jiao, G., & Zhang, D. (2025). High-Sensitivity, Low Detection Limit, and Fast Ammonia Detection of Ag-NiFe2O4 Nanocomposite and DFT Study. Nanomaterials, 15(14), 1088. https://doi.org/10.3390/nano15141088

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop