Rapid and Reversible Sensing Performance of Hydrogen-Substituted Graphdiyne

N-doped graphdiyne derivative for highly selective and ultrasensitive NH3 sensing at room temperature

The detection of ammonia (NH3) at room temperature is of paramount importance for human health, production safety, and environmental protection. However, the application of common NH3-sensitive materials is seriously limited by their low sensitivity and poor selectivity. Herein, starting from molecular structure design, an N-doped graphdiyne derivative (N-GDYD) with a definite N-doping site was synthesized via the Glaser coupling of 2,4,6-tris((trimethylsilyl) ethynyl)-1,3,5-triazine. Owing to the rich ethynyl groups and triazine N atoms, the N-GDYD gas sensor showed excellent NH3 sensing performance at room temperature (20 °C). For instance, it possessed a high response value of -67.7%, an extremely short response time of 92 s, and a short recovery time of 280 s for 100 ppm NH3. Although the NH3 concentration decreased to 10 ppb, it still exhibited a response of -12.4%. In particular, the N-GDYD gas sensor exhibited a specific response to NH3 and showed negligible responses to 13 other types of gases and organic reagent vapors. In situ UV-vis spectra and DFT calculation results confirmed that the alkyne bond and N atoms in the triazine ring were the adsorption sites for NH3. These active sites have strong interactions with NH3 and thus promoted electron transportation from the NH3 molecules to N-GDYD. Evidently, this work provides a new strategy for the design of high-performance NH3 sensing materials.

Uniform Synthesis of Bilayer Hydrogen Substituted Graphdiyne for Flexible Piezoresistive Applications

Graphdiyne (GDY) has garnered significant attention as a cutting-edge 2D material owing to its distinctive electronic, optoelectronic, and mechanical properties, including high mobility, direct bandgap, and remarkable flexibility. One of the key challenges hindering the implementation of this material in flexible applications is its large area and uniform synthesis. The facile growth of centimeter-scale bilayer hydrogen substituted graphdiyne (Bi-HsGDY) on germanium (Ge) substrate is achieved using a low-temperature chemical vapor deposition (CVD) method. This material's field effect transistors (FET) showcase a high carrier mobility of 52.6 cm2 V-1 s-1 and an exceptionally low contact resistance of 10 Ω µm. By transferring the as-grown Bi-HsGDY onto a flexible substrate, a long-distance piezoresistive strain sensor is demonstrated, which exhibits a remarkable gauge factor of 43.34 with a fast response time of ≈275 ms. As a proof of concept, communication by means of Morse code is implemented using a Bi-HsGDY strain sensor. It is believed that these results are anticipated to open new horizons in realizing Bi-HsGDY for innovative flexible device applications.

Highly Sensitive Near-Field Electrochemical Sensor for In Vivo Monitoring of Respiratory Patterns

Real-time tracking of respiratory patterns provides noninvasive and quick access for evaluating pathophysiological conditions yet remains challenging due to limited temporal resolution and poor sensitivity to dig out fingerprints of respiratory waveforms. Here, we report an electrochemical sensor for accurately tracing respiratory patterns of small animal models based on the electrochemical impedance mechanism for wireless coupling of a graphdiyne oxide (GYDO)-modified sensing coil chip and a reader coil chip via near-field magnetic induction. In the electrochemical impedance measurement mode, an alternating current is applied through the reader coil chip to perturb proton transport at the GYDO interface of the sensing coil chip. As demonstrated, a high-frequency perturbing condition significantly reduces the interfacial resistance for proton transport by 5 orders of magnitude under 95% relative humidity (RH) and improves the low-humidity responses with a limit of detection down to 0.2% RH, enabling in vivo accurate profiling of respiratory patterns on epileptic rats. The electrochemical impedance coupling system holds great potential for new wireless bioelectronics.