Low Concentrations Of Formaldehyde Research Articles

Zinc oxide-based sensor prepared by modified sol-gel route for detection of low concentrations of ethanol, methanol, acetone, and formaldehyde

Abstract We successfully synthesized zinc oxide (ZnO) nanoparticles using the sol-gel method, followed by their application onto alumina substrates for sensor testing. Comprehensive characterization of the nanomaterials was carried out utilizing XRD, SEM, TEM, UV–VIS-IR, and PL techniques. The nanoparticles displayed a hexagonal wurtzite crystal structure, typical of ZnO. UV–Vis–IR spectroscopy revealed significant absorption in the UV region, with the band gap energy calculated to be 3.22 eV. Photoluminescence (PL) spectra indicated the presence of various defects, such as oxygen vacancies and zinc interstitials, within the ZnO structure. SEM analysis of the deposited film surface showed spherical agglomerates, confirming the nanoscale dimensions, while EDX spectra affirmed the high purity of the ZnO films, rich in Zn and O elements. Sensor tests demonstrated the ZnO sensor's high sensitivity to low concentrations of volatile organic compounds (VOCs) such as ethanol, formaldehyde, methanol, and acetone. Notably, at an operational temperature of 300°C, the sensor exhibited a remarkable response to 5 ppm of each gas, with the following response and response/recovery times: for methanol, 11.47 and 36 s/57 s; for acetone, 11.54 and 25 s/52 s; for formaldehyde, 0.79 and 53 s/58 s; and for ethanol, 3.88 and 9 s/59 s.

Heterojunction photocatalyst MnO2-CsSnI3 for highly efficient formaldehyde oxidation at room temperature

The effective removal of the low-concentration formaldehyde (HCHO) in the indoor environment is a critical issue affecting the quality of people’s daily lives. In this study, heterojunction catalysts composed of manganese dioxide (MnO2) and cesium tin iodine (CsSnI3) nanocrystals were first synthesized and successfully used for photocatalytic HCHO degradation. After the full band light irradiation (150 mW/cm2) for 3 h, the concentration of HCHO decreased from 7 ppm to a minimum of 0.03 ppm at room temperature (25 °C, 25 % RH, degradation efficiency reaches up to 99.6 %). Subsequent analysis using electron paramagnetic resonance (EPR) and transmission electron microscopy (TEM) revealed that the MnO2-CsSnI3 heterojunction photocatalyst not only offers a Z-scheme charge-transfer pathway but also promotes the generation of a large number of •O2− and •OH. Compared to the single-phase material, the concentration of •O2− and •OH has increased by 1.5 times. This MnO2-based Z-scheme heterojunction photocatalyst provides a novel strategy for the degradation of low-concentration HCHO in practical indoor environments.

Synthesis, characterization and sensing applications of TiO2 doped MOF composites for selective detection of ammonia at room temperature

Herein, we have developed a highly sensitive chemiresistive TiO2 doped metal–organic framework(MOF) composite-based sensor for ammonia detection at room temperature. Two novel Ti-MOFs@TiO2 composites are developed employing terephthalic acid and 2-amino terephthalic acid as organic linkers with Titanium tetra isopropoxide (TTIP) as a metal source by solvothermal technique. The morphology and crystallinity of synthesized compounds were characterized by using Field-emission scanning electron microscopy (FE-SEM) with EDX analysis, X-ray diffraction (PXRD), XPS and Brunauer–Emmett–Teller (BET) analysis techniques. MIL-125@TiO2 sensors exhibited a more specific surface area (374.74 m2 g−1) than the other three compounds. For gas-sensing applications, all composite materials were exposed to different gas vapours like ammonia, formaldehyde, acetic acid, ethyl alcohol, acetone, xylene, toluene and benzene at room temperature. The sensing results indicate that the sensors exhibit excellent response at low concentrations of ammonia, formaldehyde and acetic acid gases (1 ppm level). The enhanced sensor response was attributed to MIL-125@TiO2 (85 response at 50 ppm) and NH2-MIL-125@TiO2 (71 response at 50 ppm) towards ammonia gas and shows a better selectivity, sensitivity and repeatability to ammonia gas. All the materials exhibited less response times (between 8 and 45 sec) and more recovery times (between 13 and 125 sec).

Highly sensitive standardized toxicity biosensors for rapid water quality warning

Microbial electrochemical sensor (MES) using electroactive biofilm (EAB) as the sensing element represents a broad-spectrum technology for early warning of biotoxicity of water samples. However, its commercial application is impeded by limited sensitivity and repeatability. Here, we proposed a layered standardized EAB (SEAB) with enriched Geobacter anodireducens SD-1 in the inner layer and self-matched outer layer. The SEAB sensors showed a 2.3 times higher sensitivity than conventional EAB acclimated directly from wastewater (WEAB). A highly repeatable response sensitivity was concentrated at 0.011 ± 0.0006 A/m2/ppm in 4 replicated batches of SEAB sensors (R2 > 0.95), highlighting their potential for reliable toxicity monitoring in practical applications. In contrast, the sensing performance of all WEAB sensors was unpredictable. SEAB also exhibited a better tolerance towards low concentration of formaldehyde, with only a 4 % loss in viability. Our findings improved the sensitivity and reproducibility of standardized MES for toxicity early warning.

Facile fabrication of nanocellulose-supported membrane composited with modified carbon nitride and HKUST-1 for efficient photocatalytic degradation of formaldehyde

As a cellulose-derived material, nanocellulose possesses unique properties that make it an ideal substrate for various functional composite materials. In this study, we developed a novel composite membrane material capable of adsorbing and photo-catalyzing formaldehyde by immobilizing HKUST-1 (copper open framework composed of 1,3,5-benzenetricarboxylic acid) onto NFC (Nano-fibrillated cellulose) membranes and subsequently loading modified carbon nitride. The synthesized CNx@HN composite membrane (consisting of NFC membrane with anchored HKUST-1 and modified g-C3Nx nanosheets) was thoroughly characterized, and its photocatalytic degradation performance towards low concentrations of formaldehyde (3.0 mg/m3) was investigated. The results demonstrated that HKUST-1's porous nature exhibited a concentrated adsorption capacity for formaldehyde, while the modified CNx (Modified g-C3Nx nanosheets) displayed robust photocatalytic degradation of formaldehyde. The synergistic effect of HKUST-1 and modified CNx on the NFC membrane significantly enhanced the efficiency of formaldehyde degradation. Under xenon lamp irradiation, CNx@HN-5 achieved a total removal efficiency of 86.9 % for formaldehyde, with a photocatalytic degradation efficiency of 48.45 %, showcasing its exceptional ability in both adsorption and photocatalytic degradation of formaldehyde. Furthermore, after 10 cycles of recycling, the composite membrane exhibited excellent stability for the photocatalytic degradation process. Therefore, this study presents a green and facile strategy to fabricate nanocellulose-supported composite membranes with great potential for practical applications in formaldehyde degradation.

Logical formulation and in-situ assembly of MnCo2O4@MnO2 nanoflower arrays on nickel foam as monolithic catalyst for formaldehyde degradation at indoor temperature

The development and design of efficient and cost-effective catalysts for oxidizing low concentrations of formaldehyde at low temperatures, has been a significant challenge in HCHO oxidation. In this study, MnCo2O4@MnO2-NF (Ni foam) was synthesized as a monolithic catalyst for the degradation of HCHO in indoor environments. Using carrier immobilization, morphology modulation, and doping modification. The results revealed that the Co3O4 nanoarrays could be grown in a directional and orderly manner on the surface of the substrate through morphological modulation, showing a pompom-like, flower-like shape of the nanoneedles, thus providing sufficient growth sites for MnO2. Doping the Co3O4 nanoarrays with Mn via in-situ growth resulted in MnCo2O4 nanoarrays, following which the MnO2 expanded the pore sizes of the sample and provide more surface adsorption sites upon using MnCo2O4 as the carrier. In addition, numerous oxygen vacancies formed on the catalyst surface because of the synergistic interaction between Co and Mn, which formed more Mn3+ species and Oads, resulting in superior low-temperature redox ability and catalytic cycle stability. The catalyst achieved a HCHO removal efficiency of over 85 % within 60 min for five test cycles when the KMnO4 concentration was 0.05 M and Mn/Co ratio was 1:2.

Humidity-tolerant sensing performance of NiO/SnO2 material for quick formaldehyde detection

As a common indoor toxic gas, formaldehyde poses a serious threat to human health. It is of great significance for the high-efficient detection of formaldehyde by non-noble metal-doped materials. In this work, we fabricated NiO-decorated SnO2 material by hydrothermal method and studied the chemosensing properties. The results indicate that NiO/SnO2-5, consisting of hollow-shaped structures self-assembled with nanoparticle, displays the enhanced response and high selectivity to formaldehyde, and the response to 100 ppm formaldehyde increased by 2.5 times. Especially, the sensor also exhibits a low operating temperature, high response to low-concentration formaldehyde and humidity-tolerant stability, implying that NiO/SnO2 material is an effective low-energy consumption material for detection of formaldehyde.

Platinum Nanoclusters-Modified Porous In2O3 Nanocubes for Highly Sensitive and Selective Formaldehyde Gas Sensing at Room Temperature

The detection of formaldehyde gas generally requires a relatively high temperature. It is still challenging to simultaneously possess high sensitivity and strong selectivity for the detection of low-concentration formaldehyde at room temperature. The activation energy of the reaction can be reduced by introducing oxygen vacancies or loading the metal clusters on the surface of metal oxide-based semiconductors, leading to an improvement in the performance and detection limit of the sensor. However, this approach may lead to an increased cross-sensitivity to other gases and a reduction in the selectivity of the sensors. In this study, In2O3 can capture a significant amount of adsorbed oxygen by increasing the oxygen vacancies and introducing platinum nanoclusters on the surface of In2O3 synthesized with a specific morphology, leading to high sensitivity and selectivity for the detection of formaldehyde gas at room temperature. The Pt-In2O3 sensor exhibits a response value of approximately 38 to a concentration of 1 ppm formaldehyde gas at 20 °C. Moreover, the developed sensor demonstrates excellent performance in a complex atmosphere and exhibits good long-term stability. The achieved high sensitivity and selectivity for the detection of formaldehyde gas at low temperatures hold significant implications for research and practical applications in the field of sensors.

Construction of hexagonal hollow rod-shaped NiCo2O4–In2O3 p-n heterojunction for low concentration formaldehyde detection

The construction of p-n heterostructures using n-type and p-type semiconductor is a very important way to enhance gas sensing performance. In this work, hexagonal rod-shaped NiCo2O4/In2O3 with larger surface area was prepared via a simple water bath approach and subsequent calcination process. The microscopic morphology characterization results show that the NiCo2O4/In2O3 composite has a hexagonal hollow rod-shaped structure, where NiCo2O4 grows in situ on the surface of In2O3, forming p-n heterojunctions. Notably, the NiCo2O4/In2O3 composites formed with 6% NiCo2O4 addition (In-NC6) at 200 °C showed the best gas sensing performance for 1 ppm formaldehyde with a response value of 9.11 and a theoretical detection limit as low as 10.83 ppb. The rich oxygen vacancies, active site and p-n heterojunction are conducive to the adsorption of formaldehyde and electron transfer. This in situ growth approach provides novel ideas and promising prospects to synthesize other p-n heterojunction materials for applying to toxic gas detection.

Revealing the critical roles of silver species on TNT film for photocatalytic decomposition of volatile organic pollutants under UV or visible light irradiation: From mechanism study to scaled-up test

Ag nanoparticles are commonly employed as co-catalysts to promote photocatalytic reactions. In addition to their apparent roles as electron traps and catalytic active sites, nanoparticulate Ag can also generate hot electrons under visible light irradiation, which endows visible light photocatalytic activity to its supporting material. On the other hand, Ag0 can be easily converted to Ag2O, however, few studies focus on its formation and roles during the photocatalytic process. In this work, we have successfully fabricated and optimized the preparation procedures of titania nanotube (TNT) and Ag species deposited TNT to get the optimum photochemical activities of Ag modified TNT. Specifically, the roles of Ag species on TNT film have been investigated by photoelectrochemical (PEC) measurements and photocatalytic decomposition of volatile organic pollutants under UV or visible light irradiation. Toluene (30 ppm) can be effectively decomposed (∼83.3%) and mineralized (∼70.7%) by Ag species modified TNT in 3 h under UV–visible light irradiation, while the degradation and mineralization ratios are only about 60.0% and 33.3% under visible light irradiation. The results demonstrate that appropriate Ag/Ag2O ratio on TNT film are crucial for improving PEC and photocatalytic performance, and the interconversion between Ag and Ag2O influences the photochemical stability of Ag/TNT film. The scaled-up tests (∼1.0 m3 reactor) on the degradation of low concentration of toluene and formaldehyde prove that the optimized Ag/TNT film can be considered as a promising photocatalyst for indoor air purification.

Zn-doped MnCe catalyst designed and applied for indoor low concentration formaldehyde removal and simultaneous antibacterial

As typical indoor air pollutants, the simultaneous removal of formaldehyde and microorganisms at room temperature was significant to purify indoor environment satisfactorily. Based on the practical problems of room temperature catalytic oxidation, Zn-doped MnCe (MC-Zn) aerogel catalysts were designed with dual functions of catalytic oxidation and bacterial inhibition in this study. It was found that MC aerogel exhibited excellent formaldehyde removal performance, which obtained 97.6% formaldehyde removal efficiency at 24 h. Besides, a small amount of Zn doping had little effect on the Lewis acidic sites and Mn3+/Mn on the MC aerogel catalyst surface, and the equivalent formaldehyde removal efficiency was achieved with the increasing specific surface area.The antibacterial tests demonstrated that the Zn-doped catalysts inhibited the growth of Staphylococcus aureus(S. aureus), Bacillus subtilis(B. subtilis) and Escherichia coli(E. coli). When the molar ratio of Mn:Zn:Ce was 5:1:4, the catalyst exhibited the optimal room temperature catalytic oxidation activity and appropriate bacterial inhibition performance. This paper provides a technical reference for the effective treatment of indoor co-contaminated environment.

Formaldehyde aggravates allergic contact dermatitis by facilitating NLRP3 inflammasome activation in macrophages.

Formaldehyde (FA) is known to be an environmental pollutant and contact sensitizer at 1% or 2% concentrations, which can induce inflammatory diseases such as allergic contact dermatitis (ACD). However, the aggravative effects of FA on ACD at legitimate low concentrations in cosmetics have not been studied. The activation of NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome in ACD was recently identified, and the inflammatory responses were attenuated by NLRP3 inhibition. Since non-cytotoxic concentrations of FA at 50 and 100μM were found to reinforce inflammatory responses in macrophages, the 0.05% low concentration of FA was applied to ACD mice induced by 2,4-dinitro-1-fluorobenzene. FA significantly exacerbated inflammatory responses and NLRP3 inflammasome activation, which was confirmed in RAW264.7 macrophages treated with FA at 50 and 100μM in vitro. Induction of mitochondrial reactive oxygen species, the common activation signal for NLRP3 inflammasome, was also observed in FA-treated macrophages. Inhibition of NLRP3 by MCC950 significantly attenuated the NLRP3 inflammasome activation induced by 100μM FA in vitro and alleviated FA-enhanced inflammatory responses in ACD mice. These results not only demonstrated that FA was able to aggravate the inflammatory responses of ACD by facilitating NLRP3 inflammasome activation in macrophages, which was likely to play important roles in FA-related sensitization, but also indicated that NLRP3 could be targeted to relieve FA-induced inflammation.

Formaldehyde Gas Sensing Characteristics of ZnO-TiO2 Gas Sensors

Since the increase in the emission of various Volatiles Organic Compounds, gas and formaldehyde gas have had a harmful effect on the human body, and gas sensors that can measure those gases were fabricated in this study. After Pt coating was performed on the alumina substrate, Zn seed layers were fabricated. Nanostructures were formed through sonochemical synthesis by varying the ratio of ZnO and TiO2. Thereafter, the reactivity and recovery properties were compared and evaluated according to the concentrations of formaldehyde and toluene gas. The ZnO(99%)-TiO2(1%) gas sensor showed meaningful selectivity of about 40% or more at a concentration ranging from 5 to 20 ppm (high concentration) of formaldehyde and toluene gas, and showed a low selectivity of about 5% or more for a concentration ranging from 0.1 to 1 ppm (low concentration) of formaldehyde and toluene gas. This sensor can be optimized to have a meaningful selectivity of formaldehyde gas compared to other Volatiles Organic Compounds gases by optimizing the ZnO-TiO2 nanostructure.

Growth of Ag/g-C3N4 nanocomposites on nickel foam to enhance photocatalytic degradation of formaldehyde under visible light

Formaldehyde is a pollutant that significantly affects the indoor air quality. However, conventional remediation approaches can be challenging to deal with low-concentration formaldehyde in an indoor environment. In this study, Photocatalysts of Ag/graphitic carbon nitride (g-C3N4)/Ni with 3D reticulated coral structure were prepared by thermal polymerization and liquid phase photo-deposition, using nickel foam (NF) as the carrier. Experiments demonstrated that when the Ag concentration was 3%, and the relative humidity was 60%, the Ni/Ag/g-C3N4 showed the maximum degradation rate of formaldehyde at 90.19% under visible light irradiation, and the formaldehyde concentration after degradation was lower than the Hygienic standard stated by the Chinese Government. The porous structure of Ni/Ag/g-C3N4 and the formation of Schottky junctions promoted the Adsorption efficiency and degradation of formaldehyde, while the nickel foam carrier effectively promoted the desorption of degradation products. Meanwhile, the degradation rate was only reduced by 3.4% after 16 recycles, the three-dimensional porous structure extended the lifetime of the photocatalyst. This study provides a new strategy for the degradation of indoor formaldehyde at low concentrations.

Adsorptivity and kinetics for low concentration of gaseous formaldehyde on bamboo-based activated carbon loaded with ammonium acetate particles

The highly promising formaldehyde (HCHO)-removing materials are essential for eliminating interior pollution to safeguard the public's health with increasing indoor HCHO contamination situations being recorded on a global scale. In the paper, bamboo charcoal (BC) was activated with boric acid to prepare bamboo-based activated carbon (BAC), and then impregnated with ammonium acetate solution to successfully develop porous adsorbent with ammonium acetate particles (N/BAC), which was applied to remove low concentration of HCHO at room temperature. The adsorption performance for HCHO was systematically investigated while the surface chemical properties and microstructure of the as-prepared adsorbents were described and analyzed. The specific surface area, total pore volume and microporous volume of N/BAC sample were 240.09 m2/g, 0.27 cm3/g and 0.12 cm3/g, which increased by 42.40 m2/g, 0.15 cm3/g and 0.03 cm3/g compared with BAC sample, respectively. The specific surface area and the microporous volume, as well as the content of oxygen- and nitrogen-containing functional groups of N/BAC sample were augmented by contrast with other samples, and numerous ammonium acetate particles were present on the surface. Precisely because of this, the N/BAC sample exhibited a high removal rate of 98.89%, which was 18.38% greater than that of BAC sample. A superior correlation coefficient (0.9999) from the experimental values of the kinetics and the fitted values of the pseudo-second-order kinetic model demonstrated that the adsorption process of HCHO on N/BAC sample was physical-chemical combined adsorption. The adsorption of HCHO on N/BAC sample was investigated under different humidity, and the results showed that the adsorbent yet had excellent adsorption capacity (87.93%) under RH 75%. Moreover, the N/BAC sample was renewable, and the removal rate still reached 82.81% after five cycles of regeneration. Therefore, the as-prepared adsorbent is an effective, economical and sustainable material, and could be used to remove HCHO from real contaminated indoor air.

Transition metal elements-doped SnO2 for ultrasensitive and rapid ppb-level formaldehyde sensing

Pristine SnO2, Fe-doped SnO2 and Ni-doped SnO2 were synthesized using facile hydrothermal method. Analysis based on XRD, TEM and UV–Vis DRS measurements demonstrated the successful insertion of Fe and Ni dopants into SnO2 crystal. Formaldehyde-detection measurements revealed that transition metal-doped SnO2 exhibited improved formaldehyde-sensing properties compared with that of pristine SnO2. When the amount of incorporated dopant (Fe or Ni) was 4 at.%, the most effective enhancement on sensing performance of SnO2 was obtained. At 160 °C, the 4 at.% Fe–SnO2 and 4 at.% Ni–SnO2 exhibited higher response values of 7.52 and 4.37 with exposure to low-concentration formaldehyde, respectively, which were 2.4 and 1.4 times higher than that of pristine SnO2. The change of electronic structure and crystal structure as well as catalytic effect of transition metals are chiefly responsible for the enhanced sensing properties.

Boosting formaldehyde catalytic oxidation of novel Au/mPVB fiber membrane with microreactor-like structure

In this study, a novel and well-constructed composite fiber membrane (Au/mPVB) is provided for removing the low-concentration formaldehyde gas continuously released in indoor environments at room temperature. The Au/mPVB provides a microreactor-like structure for catalytic reaction, in which the fiber has a homogeneous macroporous structure, and Au NPs are uniformly loaded onto the inner wall of the macropores in the amino-modified fiber (mPVB) by template sacrifice. Formaldehyde can be enriched in the mPVB fiber under the adsorption to the amino groups, and the catalytic performance can be improved effectively under the synergistic effect of adsorption and catalysis. In the experimental results of performance tests, 1 wt% Au/mPVB exhibited a high removal efficiency of 97.5% for 0.8 ppm formaldehyde in the indoor environment, which improved the performance by 25% compared to mPVB, and no obvious decrease of catalytic activation occurred after the continuous formaldehyde-releasing experiment without catalyst regeneration.

A Ratiometric Fluorescent Nanoprobe for Ultrafast Detection of Formaldehyde in Wood and Food Samples

AbstractFluorescent sensing of formaldehyde (FA) in the environment is of great significance for human health. However, the development of ratiometric fluorescent probes for ultrasensitive FA detection is challenging due to the lack of suitable strategies. In this study, we demonstrate that ratiometric FA nanoprobes can be facile constructed by integrating two simultaneously excitable fluorophores into a polymer matrix. Using this strategy, we developed a ratiometric fluorescent nanoprobe (Nano‐FAP‐1) for the highly sensitive detection of FA in environmental samples by incorporating a 4‐hydrazino‐1,8‐naphthalimide derivative (Na‐FA) as the receptor and 7‐diethylaminocoumarin‐3‐carboxyl ethyl acetate (Cou‐1) as the reference into a Pluronic F‐127 matrix. The probe achieved a highly sensitive and selective response to low concentrations of FA, with a response time of fewer than 5 s and a detection limit of 0.407 μM. It is worth noting that the probe can be used for the determination of FA in wood and food samples, demonstrating its potential application in the field of toxic gas monitoring and environmental protection.

SnO2 mesoporous nanoparticle-based gas sensor for highly sensitive and low concentration formaldehyde detection.

Indoor air quality detection, especially formaldehyde (HCHO) detection, is of great importance in practical application. A key limitation of promoting gas-sensing devices is the lack of sensing materials with high sensing sensitivity and selectivity. In this study, SnO2 mesoporous nanoparticles are fabricated by a facile hydrothermal route with a subsequent acid etching process. The prepared samples show high response toward HCHO (133.5, 222.8 for 100 ppm and 200 ppm HCHO, respectively) and short response/recovery time (15/22 s at 10 ppm). The excellent HCHO sensing performance benefits from the comprehensive regulation of the depletion region width, surface area and rich porosity, which is effective for the promotion of surface adsorption and catalyst activity. It is expected that the excellent sensing properties are promising for practical HCHO gas detection.

Ag-promoted Cr/MnO2 catalyst for catalytic oxidation of low-concentration formaldehyde at room temperature.

As one of the significant pollutants in indoor air, formaldehyde (HCHO) has attracted increasing attention due to its negative effects on human health. Thus, to reduce formaldehyde pollution, herein, an Ag-promoted Cr/MnO2 catalyst (Ag/Cr/MnO2) was obtained via a hydrothermal-calcination method, which was employed for the catalytic oxidation of low-concentration indoor HCHO (∼1 ppm) at room temperature. The Ag/Cr/MnO2 catalyst eliminated approximately 98.62% HCHO within 14 h and maintained a high removal efficiency continuously under the dynamic test conditions. Furthermore, the catalyst exhibited good recycling stability and outstanding activity in a humid environment. Different characterization techniques were utilized to determine the physicochemical properties that contribute to improving the catalytic performance. The Ag substance contained metallic Ag (Ag0) as the main component and some Ag2O, and the Ag0 particles provided ample active sites for the catalytic oxidation of HCHO. Besides, the incorporation of Ag increased the reducibility of the catalyst and the content of Mn4+, Cr6+ and oxygen vacancies. The abundant active sites, high reducibility, rich Mn4+, Cr6+, oxygen vacancies, and surface lattice oxygen species, and the powerful interaction between Cr/MnO2 and Ag were the reasons for the splendid catalytic capability for HCHO by the Ag/Cr/MnO2 catalyst. In conclusion, the Ag/Cr/MnO2 catalyst can be a promising catalyst to degrade HCHO with practical application significance.