Atomically Dispersed Au on In2O3 Nanosheets for Highly Sensitive and Selective Detection of Formaldehyde

Defects-rich Ru-doped black TiO2 nanotube arrays for photoelectrochemical levofloxacin degradation coupled with simultaneous cathodic H2 production

As an emerging and promising technology, the bifunctional photoelectrocatalytic (PEC) systems have shown remarkable potential in treating wastewater and producing energy. A central critical challenge in this field is the development of high-performance electrode materials that exhibit superior PEC properties. In this work, the defect-rich Ru-doped black TiO2 nanotube arrays (Ru-BTNAs) bifunctional electrodes were engineered and utilized in a PEC system, aiming to achieve efficient antibiotics levofloxacin degradation and hydrogen production simultaneously. In-depth characterization characterizations and the Density functional theory (DFT) calculations reveal that the synergistic effect between Ti3+-oxygen vacancies (Ovs) defects and Ru doping significantly improves light absorption, accelerates the separation and transmission of photoexcited e--h+ pairs, and optimizes PEC performance. The coupled photocatalytic and electrocatalytic processes enhance the generation of h+, 1O2, HO•, and SO4•- radicals, which effectively degrade levofloxacin. The abundant Ovs facilitate electron transfer from BTNAs to Ru, accelerating hydrogen evolution reaction (HER) on electron-rich Ru at a low overpotential. This work provides a theoretical framework for designing bifunctional electrode to achieve the energy-efficient hydrogen production from antibiotics-contaminated wastewater.

Ionic liquid-assisted synthesis of In2O3 nanoparticles for ultra-fast detection of unsymmetrical dimethylhydrazine

Due to the unique physiochemical properties of ionic liquids, they are extensively used as agent or solvent in the synthesis process of nanomaterials. The tailored growth process of functional nanomaterials might result in performance modification for them. In this work, In2O3 nanoparticles were prepared via the hydrothermal method and subsequent calcination (400 °C, 500 °C, 600 °C and 700 °C). An ionic liquid (1-hexadecyl-3-methylimidazolium chloride, [C16Mim] Cl) was introduced in the hydrothermal process. After calcination, trace of [C16Mim] Cl inclusion in In2O3 was pyrolyzed with Cl residue (Cl-In2O3). In compare with control sample synthesized without [C16Mim] Cl (pure In2O3), In2O3-600 (Cl-In2O3 calcined at 600 °C) exhibited an excellent UDMH sensing performance at 225 °C. The fabricated sensor achieved a high response value (71.0 ± 2.1 to 100 ppm), rapid response time (2 s), good selectivity and a low theoretical limit of detection (1.72 ppb) to UDMH gas. Various characterizations, in regard to oxygen vacancy, surface texture structure, energy band structure and surface acidity, were utilized to analyze the cause for enhanced performance. The ionic liquid inclusion increases the contents of adsorbed oxygen species and improves the adsorption capacity to UDMH gas. This work indicates that the synthesized In2O3 nanoparticles could be the potential candidates for rapid UDMH detection in some specific application scenarios.

Advancements in porous framework materials for chemiresistive hydrogen sensing: exploring MOFs and COFs

Hydrogen is a zero-emissive fuel and has immense potential to replace carbon-emitting fuels in the future. The development of efficient H2 sensors is essential for preventing hazardous situations and facilitating the widespread usage of hydrogen. Chemiresistors are popular gas sensors owing to their attractive properties such as fast response, miniaturization, simple integration with electronics and low cost. Traditionally, semiconducting metal oxides (SMOs) and Pd-based materials have been widely investigated for chemiresistive H2 sensing applications. However, issues such as limited selectivity and poor reliability still hinder their use in real-time applications. Recent advancements have explored metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), offering new perspectives and potential applications in this field. MOFs and COFs belong to the crystalline framework (CF) family of materials and are highly porous, designable materials with tunable pore surfaces featuring sites for H2 interactions. They exhibit good selectivity towards H2 with quick response/recovery times at relatively low temperatures compared to SMOs. Furthermore, they provide an additional advantage of sensing H2 in the absence of oxygen, even at high concentrations of H2. In this perspective article, we summarize recent advancements and challenges in the development of H2 sensors employing MOFs, COFs, and their hybrid composites as sensing elements. Additionally, we discuss our perspective on hybridizing MOFs/COFs with SMOs and other nanomaterials for the future development of advanced H2 sensors.

Unveiling the Role of Strong Metal-Support Interactions in Gold-Catalyzed CO Oxidation on MnO2 Polymorphs

The effectiveness of gold (Au)-based catalysts in CO oxidation is significantly influenced by strong metal-support interactions with surface oxygen structures, the mechanisms of which remain elusive. To investigate this property, we selected γ-MnO2, featuring Mn(-O-)2Mn and Mn-O-Mn structural motifs, and β-MnO2, characterized by Mn-O-Mn linkages, as support materials. The CO oxidation process was investigated by fabricating Au nanoparticles supported on these two MnO2 polymorphs. Our findings reveal that Au supported on β-MnO2 substantially enhanced CO oxidation, in stark contrast to the inhibitory effect observed with Au on γ-MnO2. Using operando diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry, we detected an increase in the production of surface-adsorbed oxygen following Au deposition on β-MnO2. Conversely, Au supported on γ-MnO2 resulted in a diminished capacity for surface oxygen adsorption. The presence of Au+ and Mn2+ ions was identified as pivotal for CO oxidation. Moreover, the engagement of the Mn(-O-)2Mn structure in the reaction was impaired after Au loading on γ-MnO2, and the regeneration of the Mn-O-Mn linkage was similarly hindered. We propose a mechanism for the interactions between Au and the oxygen species associated with Mn(-O-)2Mn and Mn-O-Mn structures on MnO2, offering insights into the divergent catalytic behaviors exhibited by different MnO2 polymorphs.

Ultrahigh humidity-resistance ppb-level formaldehyde sensing at room temperature induced by fluorinated dipole based "umbrella" and "bridge"

Formaldehyde (HCHO) is a major indoor pollutant that is extremely harmful to human health even at ppb-level. Meanwhile, ppb-level HCHO is also a potential disease marker in the exhalation of patients with respiratory diseases. Higher humidity resistance and lower practical limit of detection (pLOD) both have to be pursued for practical HCHO sensors. In this work, by assembling indium oxide (In2O3) and fluorinated dipole modified reduced graphene oxide (rGO), we prepared a high-performance room temperature HCHO sensor (In2O3 @ATQ-rGO). Excellent sensing properties toward HCHO under visible illumination have been achieved, including ultra-low pLOD of 3 ppb and high humidity-resistance. By control experiments and density functional theory calculation, it is indicated that the introduced fluorinated dipoles act as not only an "umbrella" to improve the humidity resistance of the composite, but also a "bridge" to accelerate the electron transport, improving the sensitivity of the material. The significant practicality and reliability of the obtained sensors were verified by in-situ simulation experiments using a 3 m3 test chamber with a humidity control system and by detection of the simulated lung disease patient's exhalation. This work provides an effective strategy of simultaneously achieving high humidity-resistance and low pLOD of room temperature formaldehyde sensing materials.

Ppb-level unsymmetrical dimethylhydrazine detection based on In2O3 hollow microspheres with Nd doping

As one of main high-energy fuels for rocket launching, unsymmetrical dimethylhydrazine (UDMH) and its decomposition products do harm to environment and human health. It is significant to develop a device to monitor its leakage. In this work, a UDMH gas sensor based on In2O3 hollow microspheres with Nd dopant was fabricated. The pure, 1.0 mol%, 3.0 mol% and 5.0 mol% Nd doped In2O3 were synthesized via one-step solvothermal method. Among them, 3.0% Nd-In2O3 based sensor exhibits the highest response toward UDMH vapor. Its response value to 100 ppm UDMH is 183.3 at optimal working temperature of 250 °C, 6.8 times higher than that of pure In2O3 (26.8). Besides high response to UDMH, the 3% Nd-In2O3 based sensor represents excellent selectivity, rapid response speed (2 s) and ultra-low theoretical LOD to UDMH (0.28 ppb). The improved gas sensing performance via Nd doping could be attributed to the enhanced specific surface area, increased concentration of adsorbed oxygen and improved adsorption capacity for UDMH molecular on the surface. The excellent sensing performance of Nd doped In2O3 hollow microspheres makes it a promising candidate for real-time UDMH detection.

Advances in Synthesis and Applications of Single-Atom Catalysts for Metal Oxide-Based Gas Sensors

As a stable, low-cost, environment-friendly, and gas-sensitive material, semiconductor metal oxides have been widely used for gas sensing. In the past few years, single-atom catalysts (SACs) have gained increasing attention in the field of gas sensing with the advantages of maximized atomic utilization and unique electronic and chemical properties and have successfully been applied to enhance the detection sensitivity and selectivity of metal oxide gas sensors. However, the application of SACs in gas sensors is still in its infancy. Herein, we critically review the recent advances and current status of single-atom catalysts in metal oxide gas sensors, providing some suggestions for the development of this field. The synthesis methods and characterization techniques of SAC-modified metal oxides are summarized. The interactions between SACs and metal oxides are crucial for the stable loading of single-atom catalysts and for improving gas-sensitive performance. Then, the current application progress of various SACs (Au, Pt, Cu, Ni, etc.) in metal oxide gas sensors is introduced. Finally, the challenges and perspectives of SACs in metal oxide gas sensors are presented.

Sensors Based on Tin and Indium Oxides for the Determination of Acetone in Human Breath

The properties of planar sensors based on tin dioxide and indium oxide used for the determination of acetone vapors have been studied. Sensors based on synthesized SnO2 and In2O3 nanopowders showed high sensitivity to low concentrations of acetone in a humid environment which simulates human exhalation. The addition of a small amount of AuIII ions to hydroxide sols significantly increases the threshold sensitivity and the sensor response in a wide range of acetone concentrations. In2O3-Au sensors have the maximum sensitivity at an operating temperature of 325 °C. The In2O3-Au-sensors reliably record the change in acetone concentration in the concentration range from a minimum of 0.1 to 5 ppm with high accuracy, which is necessary for rapid diagnostics of the condition of patients with diabetes (1.8-5.0 ppm). The high sensitivity of the obtained sensors is explained by the structural features and the surface conditions of oxides and gold nanoparticles, which depend on the sample synthesis conditions.

Pt-Pd Nanoalloys Functionalized Mesoporous SnO2 Spheres: Tailored Synthesis, Sensing Mechanism, and Device Integration

Methane (CH4 ), as the vital energy resource and industrial chemicals, is highly flammable and explosive for concentrations above the explosive limit, triggering potential risks to personal and production safety. Therefore, exploiting smart gas sensors for real-time monitoring of CH4 becomes extremely important. Herein, the Pt-Pd nanoalloy functionalized mesoporous SnO2 microspheres (Pt-Pd/SnO2 ) were synthesized, which show uniform diameter (≈500 nm), high surface area (40.9-56.5 m2 g-1 ), and large mesopore size (8.8-15.8 nm). The highly dispersed Pt-Pd nanoalloys are confined in the mesopores of SnO2 , causing the generation ofoxygen defects and increasing the carrier concentration of sensitive materials. The representative Pt1 -Pd4 /SnO2 exhibits superior CH4 sensing performance with ultrahigh response (Ra /Rg = 21.33 to 3000 ppm), fast response/recovery speed (4/9 s), as well as outstanding stability. Spectroscopic analyses imply that such an excellent CH4 sensing process involves the fast conversion of CH4 into formic acid and CO intermediates, and finally into CO2 . Density functional theory (DFT) calculations reveal that the attractive covalent bonding interaction and rapid electron transfer between the Pt-Pd nanoalloys and SnO2 support, dramatically promote the orbital hybridization of Pd4 sites and adsorbed CH4 molecules, enhancing the catalytic activation of CH4 over the sensing layer.

Large-Area and Visible-Light-Driven Heterojunctions of In2O3/Graphene Built for ppb-Level Formaldehyde Detection at Room Temperature

Achieving convenient and accurate detection of indoor ppb-level formaldehyde is an urgent requirement to ensure a healthy working and living environment for people. Herein, ultrasmall In₂O₃ nanorods and supramolecularly functionalized reduced graphene oxide are selected as hybrid components of visible-light-driven (VLD) heterojunctions to fabricate ppb-level formaldehyde (HCHO) gas sensors (named InAG sensors). Under 405 nm visible light illumination, the sensor exhibits an outstanding response toward ppb-level HCHO at room temperature, including the ultralow practical limit of detection (pLOD) of 5 ppb, high response (R_a/R_g = 2.4, 500 ppb), relatively short response/recovery time (119 s/179 s, 500 ppb), high selectivity, and long-term stability. The ultrasensitive room temperature HCHO-sensing property is derived from visible-light-driven and large-area heterojunctions between ultrasmall In₂O₃ nanorods and supramolecularly functionalized graphene nanosheets. The performance of the actual detection toward HCHO is evaluated in a 3 m³ test chamber, confirming the practicability and reliability of the InAG sensor. This work provides an effective strategy for the development of low-power-consumption ppb-level gas sensors.

Progress and Perspectives of Single-Atom Catalysts for Gas Sensing

Single-atom catalysts (SACs) attract extensive attention in the field of heterogeneous catalysis in recent years due to the maximum atom utilization and unique physical and chemical properties. The gas sensing is actually a heterogeneous catalysis process but the SACs are new to this area. Although SACs show huge potential in gas sensing, the SACs gas sensing area currently is still at the infancy stage. This work critically reviews the recent advances and current status of single-atom gas sensing materials. General synthesis routes, characterization methods, and sensing performance indexes are introduced. At the end, the challenges and future prospects on SACs gas sensing are presented from the authors' perspectives. This work is anticipated to provide insights and guideline for the chemical sensing community.

Development of a Conductometric Sensor Based on Al,Ca-Doped ZnO for the Detection of Formaldehyde

In the present study, the development of a conductometric gas sensor based on Al,Ca-doped zinc oxide composite which is finalized to the detection of formaldehyde (HCHO) at a low concentration in air is investigated. The electrical and sensing properties of the composite based on ZnO doped with different loadings of Al and/or Ca (from 0 up to 5 at%) were evaluated. The gas-sensing mechanism of Al,Ca-doped zinc oxide nanocomposite-based sensors was also discussed. The optimized 3%Al,3%Ca-ZnO sensor displayed a formaldehyde response of 3.5 (@ 4 ppm HCHO/air) and an experimental low detection limit of 125 ppb HCHO/air, at the operating temperature of 400 °C. The sensor was also shown to be selective to HCHO with respect to many interferent indoor gases, but NO₂ changed the baseline resistance in an opposite way compared to the target gas. The developed device for monitoring HCHO in indoor and workplace environments has the advantage of a simple planar structure and can be easily fabricated for mass production by using low-cost materials and easy fabrication methods.

Emerging single atom catalysts in gas sensors

Single atom catalysts (SACs) offer unprecedented opportunities for high-efficiency reactions taking place in many important fields of catalytic processes, electrochemistry, and photoreactions. Due to their maximized atomic utilization and unique electronic and chemical properties, SACs can provide high activity and excellent selectivity for gas adsorption and electron transport, leveraging SACs that enhance the detection sensitivity and selectivity to target gases. In the past few years, SACs including both noble (Pt, Pd, Au, etc.) and non-noble (Mn, Ni, Zn etc.) metals have been demonstrated to be very useful in optimizing sensing performances. However, a comprehensive review on this topic is still missing. Herein, we summarize the synthesis technologies of SACs that are applicable to gas sensors. The electronic and chemical interactions between SACs and host sensing materials, which are crucial to sensor functions, are discussed. Then, we highlight the application progress of various SACs in gas sensors. Prospects in the creation of new sensing materials with emerging SACs and versatile supports are also present. Finally, the challenges and prospects of SACs in the future development of sensors are analyzed.

Improved TEA Sensitivity and Selectivity of In2O3 Porous Nanospheres by Modification with Ag Nanoparticles

A highly sensitive and selective detection of volatile organic compounds (VOCs) by using gas sensors based on metal oxide semiconductor (MOS) has attracted increasing interest, but still remains a challenge in gas sensitivity and selectivity. In order to improve the sensitivity and selectivity of In2O3 to triethylamine (TEA), herein, a silver (Ag)-modification strategy is proposed. Ag nanoparticles with a size around 25–30 nm were modified on pre-synthesized In2O3 PNSs via a simple room-temperature chemical reduction method by using NaBH4 as a reductant. The results of gas sensing tests indicate that after functionalization with Ag, the gas sensing performance of In2O3 PNSs for VOCs, especially for TEA, was remarkably improved. At a lower optimal working temperature (OWT) of 300 °C (bare In2O3 sensor: 320 °C), the best Ag/In2O3-2 sensor (Ag/In2O3 PNSs with an optimized Ag content of 2.90 wt%) shows a sensitivity of 116.86/ppm to 1–50 ppm TEA, about 170 times higher than that of bare In2O3 sensor (0.69/ppm). Significantly, the Ag/In2O3-2 sensor can provide a response (Ra/Rg) as high as 5697 to 50 ppm TEA, which is superior to most previous TEA sensors. Besides lower OWT and higher sensitivity, the Ag/In2O3-2 sensor also shows a remarkably improved selectivity to TEA, whose selectivity coefficient (STEA/Sethanol) is as high as 5.30, about 3.3 times higher than that of bare In2O3 (1.59). The sensitization mechanism of Ag on In2O3 is discussed in detail.

Atomically Dispersed Pt on Three-Dimensional Ordered Macroporous SnO2 for Highly Sensitive and Highly Selective Detection of Triethylamine at a Low Working Temperature

Triethylamine (TEA) is a widely used volatile organic chemical, which is harmful and can cause headache, dizziness, and respiratory discomfort. Developing an efficient sensor to detect trace amounts of TEA is significant for industrial and healthcare monitoring. In this work, SnO₂ with a three-dimensional ordered macroporous structure (3DOM) was prepared through a polymethylmethacrylate sphere template route. The TEA sensing performance of the 3DOM SnO₂ was enhanced through Pt loading. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy images and X-ray absorption fine-structure analysis indicate that Pt on the 3DOM 0.20% Pt/SnO₂ surface mainly exists in the state of atomic dispersion, which results in more active sites, higher Hall mobility and active oxygen contents, and lower response energy barriers. The 0.20% Pt/SnO₂ sensor has a low operating temperature of 80 °C and a low limit of detection (0.32 ppb). Because of the uniform adsorption of TEA on the atomically dispersed Pt, the 3DOM Pt/SnO₂ sensor exhibits high selectivity.

Ultra-sensitive H2S sensor based on sunflower-like In-doped ZnO with enriched oxygen vacancies

In–ZnO with oxygen vacancies exhibits a higher sensing response and a shorter recovery time for H2S compared to ZnO.

Enhanced Blocking Effect: A New Strategy to Improve the NO2 Sensing Performance of Ti3C2Tx by γ-Poly(l-glutamic acid) Modification

Titanium carbide (Ti₃C₂T_x) with a distinctive structure, abundant surface chemical groups, and good electrical conductivity has shown great potential in fabricating superior gas sensors, but several challenges, such as low response kinetics, poor reversibility, and serious baseline drift, still remain. In this work, γ-poly(l-glutamic acid) (γ-PGA) with a blocking effect is exploited to modify Ti₃C₂T_x, thereby stimulating the positive response behavior of Ti₃C₂T_x and improving its gas sensing performance. On account of the unique synergetic interaction between Ti₃C₂T_x and γ-PGA, the response of the flexible Ti₃C₂T_x/γ-PGA gas sensor to 50 ppm NO₂has been improved to a large extent (average 1127.3%), which is 85 times that of Ti₃C₂T_x (only 13.2%). Moreover, the as-fabricated Ti₃C₂T_x/γ-PGA sensor not only exhibits a shorter response/recovery time (average 43.4/3 s) compared with the Ti₃C₂T_x-based sensor (∼18.5/18.3 min) but also shows good reversibility and repeatability (relative standard deviation (RSD) <1%) at room temperature within 50% relative humidity (RH). The improved gas sensing properties of the Ti₃C₂T_x/γ-PGA sensor can be attributed to the enhancement of effective adsorption and the blocking effect assisted by water molecules. Furthermore, the gas sensing response of the Ti₃C₂T_x/γ-PGA sensor is studied at different RHs, and humidity compensation of the sensor is carried out using the multiple regression method. This work demonstrates a novel strategy to enhance the gas sensing properties of Ti₃C₂T_x by γ-PGA modification and provides a new way to realize highly responsive gas detection at room temperature.

Strategies for Improving the Sensing Performance of Semiconductor Gas Sensors for High-Performance Formaldehyde Detection: A Review

Formaldehyde is a poisonous and harmful gas, which is ubiquitous in our daily life. Long-term exposure to formaldehyde harms human body functions; therefore, it is urgent to fabricate sensors for the real-time monitoring of formaldehyde concentrations. Metal oxide semiconductor (MOS) gas sensors is favored by researchers as a result of their low cost, simple operation and portability. In this paper, the mechanism of formaldehyde detection by gas sensors is introduced, and then the ways of ameliorating the response of gas sensors for formaldehyde detection in recent years are summarized. These methods include the control of the microstructure and morphology of sensing materials, the doping modification of matrix materials, the development of new semiconductor sensing materials, the outfield control strategy and the construction of the filter membrane. These five methods will provide a good prerequisite for the preparation of better performing formaldehyde gas sensors.

Boosting Room Temperature Sensing Performances by Atomically Dispersed Pd Stabilized via Surface Coordination

The urgent requirement of monitoring air pollution worldwide evokes intensive research interest in developing chemiresistive gas sensing techniques. To overcome the limits in sensitivity and selectivity of room temperature (RT) chemiresistive sensing materials, a new strategy using single-atom catalysts (SACs) via surface coordination is proposed. As a proof-of-concept, single Pd atoms on TiO₂ (Pd₁-TiO₂) possess high efficiency in generating adsorbed O₂^- as well as high activity and selectivity in catalyzing CO oxidation at RT. As a result, Pd₁-TiO₂ shows record high sensitivity among the reported RT sensing materials, which is even comparable to those of the best materials working at high temperature. It also provides an approximately 1 order of magnitude lower limit of detection than the best CO sensing materials. Moreover, Pd₁-TiO₂ presents high selectivity toward 12 kinds of interference gases. This work not only paves a way to design high-performance RT gas sensing materials but also extends the application of SACs.

Ozone Sensing by In2O3 Films Modified with Rh: Dimension Effect

We considered the effect of coverage of the surface of In₂O₃ films with rhodium on the sensitivity of their electrophysical properties to ozone (1 ppm). The surface coverage with rhodium varied in the range of 0–0.1 ML. The In₂O₃ films deposited by spray pyrolysis had a thickness of 40–50 nm. The sensor response to ozone depends on the degree of rhodium coverage. This dependence has a pronounced maximum at a coverage of ~0.01 ML of Rh. An explanation is given for this effect. It is concluded that the observed changes are associated with the transition from the atomically dispersed state of rhodium to a 3D cluster state.

Inorganic-Diverse Nanostructured Materials for Volatile Organic Compound Sensing

Environmental pollution related to volatile organic compounds (VOCs) has become a global issue which attracts intensive work towards their controlling and monitoring. To this direction various regulations and research towards VOCs detection have been laid down and conducted by many countries. Distinct devices are proposed to monitor the VOCs pollution. Among them, chemiresistor devices comprised of inorganic-semiconducting materials with diverse nanostructures are most attractive because they are cost-effective and eco-friendly. These diverse nanostructured materials-based devices are usually made up of nanoparticles, nanowires/rods, nanocrystals, nanotubes, nanocages, nanocubes, nanocomposites, etc. They can be employed in monitoring the VOCs present in the reliable sources. This review outlines the device-based VOC detection using diverse semiconducting-nanostructured materials and covers more than 340 references that have been published since 2016.

Single-atom catalysts boost signal amplification for biosensing

Development of highly sensitive biosensors has received ever-increasing attention over the years. Due to the unique physicochemical properties, the functional nanomaterial-enabled signal amplification strategy has made some great breakthroughs in biosensing. However, the sensitivity and selectivity still need further improvement. Single-atom catalysts (SACs) containing atomically dispersed metal active sites demonstrate distinctive advantages in catalytic activity and selectivity for various catalytic reactions. As a consequence, the SAC-enabled signal amplification strategy holds great promise in biosensors, demonstrating satisfactory sensitivity and selectivity with the assistance of tunable metal-support interactions, coordination environments and geometric/electronic structures of active sites. In this tutorial review, we briefly discuss the structural advantages of SACs. Then, the catalytic mechanism at the atomic scale and signal amplification effects of SACs in the colorimetric, electrochemical, chemiluminescence, electrochemiluminescence, and photoelectrochemical biosensing applications are highlighted in detail. Finally, opportunities and challenges to be faced in the future development of the SAC-enabled signal amplification strategy for biosensing are discussed and outlooked.

Bi-Underpotential/PtAu-bulk co-electrodeposition and subsequent Bi dissolution for the electrocatalytic oxidation and amperometric analysis of formaldehyde

A PtAuBi-UPD composite electrocatalyst modified glassy carbon electrode (GCE) is prepared via the simultaneous underpotential deposition (UDP) of Bi and bulk deposition of Pt and Au, followed by stripping of the accessible Bi, and it shows high performance for the electrocatalytic oxidation and amperometric analysis of formaldehyde.