Phenyl-Modified Carbon Nitride Quantum Nanoflakes for Ultra-Highly Selective Sensing of Formic Acid: A Combined Experimental by QCM and Density Functional Theory Study

Abstract

Formic acid (HCOOH) is an important intermediate in chemical synthesis, pharmaceuticals, the food industry, and leather tanning and is considered to be an effective hydrogen storage molecule. Direct contact with its vapor and its inhalation lead to burns, nerve injury, and dermatosis. Thus, it is critical to establish efficient sensing materials and devices for the rapid detection of HCOOH. In the present study, we introduce a chemical sensor based on a quartz crystal microbalance (QCM) sensor capable of detecting trace amounts of HCOOH. This sensor is composed of colloidal phenyl-terminated carbon nitride (Ph-g-C3N4) quantum nanoflakes prepared using a facile solid-state method involving the supramolecular preorganization technology. In contrast to other synthetic methods of modified carbon nitride materials, this approach requires no hard templates, hazardous chemicals, or hydrothermal treatments. Comprehensive characterization and density functional theory (DFT) calculations revealed that the QCM sensor designed and prepared here exhibits enhanced detection sensitivity and selectivity for volatile HCOOH, which originates from chemical and hydrogen-bonding interactions between HCOOH and the surface of Ph-g-C3N4. According to DFT results, HCOOH is located close to the cavity of the Ph-g-C3N4 unit, with bonding to graphitic carbon and pyridinic nitrogen atoms of the nanoflake. The sensitivity of the Ph-g-C3N4-nanoflake-based QCM sensor was found to be the highest (128.99 Hz ppm–1) of the substances studied, with a limit of detection (LOD) of HCOOH down to a sub-ppm level of 80 ppb. This sensing technology based on phenyl-terminated attached-g-C3N4 nanoflakes establishes a simple, low-cost solution to improve the performance of QCM sensors for the effective discrimination of HCOOH, HCHO, and CH3COOH vapors using smart electronic noses.

High-Sensitivity and Environmentally Friendly Humidity Sensors Deposited with Recyclable Green Microspheres for Wireless Monitoring

“…Further increasing the mass of the SA/PGA GMs can increase the sensitivity to 55. 9 (Figure S8), while the sensitivity of CHSs sold on the market is usually 0.1 pF/% RH. 43 Furthermore, in comparison to the temperature change-affected RHSs, NQHSs have a wider range of application scenarios and are not sensitive to ambient temperature (Figure S9).…”

“…Compared with CHSs and RHSs, quartz crystal microbalance (QCM)-based humidity sensors (QHSs) can significantly increase the humidity measurement precision and lower the detection limit to the nanogram level based on the piezoelectric effect. The humidity-detection mechanism proposed by Sauerbery in 1959 is expressed as eq . , where f 0 is the basic resonance frequency, A is the working area of the electrode, and ρ and μ are the density and shear modulus, respectively. Because f 0 , A , and ρ and μ can be regarded as constants for the same QCM, the resonance frequency shift (Δ f ) depends on the mass change (Δ m ) between before and after adsorbing water vapor.…”

“…QHSs generally exhibit advantages of insensitivity to ambient temperature, a wide detection range, and fast response/recovery. − Precision measurements can be achieved if the base frequency of QCM is above megahertz (MHz). Therefore, QCM has been used as the substrate for preparing high-sensitive sensors in many fields, such as environment, biology, chemistry, and physics. ,− …”

Prospect of DFT Utilization in Polymer-Graphene Composites for Electromagnetic Interference Shielding Application: A Review

“…A number of works in the literature have reported DFT utilization, although not for EMI shields in these materials systems [53,54]. In this light, g-C 3 N 4 nanoribbons characteristics, as well as the correlation between the structural architecture or other factors and their properties, have been investigated by means of DFT [55][56][57][58].…”

Analysis of the Effect of Electrode Materials on the Sensitivity of Quartz Crystal Microbalance

“…The quartz crystal microbalance (QCM), consisting of a vibrating quartz thin wafer sandwiched between two metal excitation electrodes, is a surface-sensitive analytical tool and a highly sensitive surface interface process analysis tool with nanogram-level sensitivity that can reflect in situ and in real time the mass changes on the surface of quartz wafers [ 1 , 2 , 3 ]. QCM’s features, including real-time monitoring, the characterization of membrane deposition, the detection of specific antigens and study of cell adhesion, and its simplicity of operation, digital output, simple back-end processing circuit and strong anti-interference ability compared to other analytical tools, mean that it is widely used in chemical, physical, material, biological and other fields [ 4 , 5 , 6 ].…”