MXenes as emerging nanomaterials in water purification and environmental remediation

Toluene is one of the harmful volatile organic compounds (VOCs) for both human health and environments. Thus, to prevent the hazardous effect of toluene, fast detection at an early stage is needed....

CuO Nanoparticles/Ti3C2Tx MXene Hybrid Nanocomposites for Detection of Toluene Gas

Along with the progress of nanoscience and nanotechnology, nanomaterials with attractive structural and functional properties have gained more attention than ever before, especially in the field of electronic sensors. In recent years, the gas sensing devices have made great achievement and also created wide application prospects, which leads to a new wave of research for designing advanced sensing materials. There is no doubt that the characteristics are highly governed by the sensitive layers. For this reason, important advances for the outstanding, novel sensing materials with different dimensional structures including 0D, 1D, 2D, and 3D are reported and summarized systematically. The sensing materials cover noble metals, metal oxide semiconductors, carbon nanomaterials, metal dichalcogenides, g-C3 N4 , MXenes, and complex composites. Discussion is also extended to the relation between sensing performances and their structure, electronic properties, and surface chemistry. In addition, some gas sensing related applications are also highlighted, including environment monitoring, breath analysis, food quality and safety, and flexible wearable electronics, from current situation and the facing challenges to the future research perspectives.

Recent Progress of Nanostructured Sensing Materials from 0D to 3D: Overview of Structure–Property-Application Relationship for Gas Sensors

A review on Ti3C2Tx-based nanomaterials: synthesis and applications in gas and humidity sensors

Hydrogen (H2) is one of the next-generation energy sources because it is abundant in nature and has a high combustion efficiency that produces environmentally benign products (H2O). However, H2/air mixtures are explosive at H2 concentrations above 4%, thus any leakage of H2 must be rapidly and reliably detected at much lower concentrations to ensure safety. Among the various types of H2 sensors, chemiresistive sensors are one of the most promising sensing systems due to their simplicity and low cost. This review highlights the advances in H2 chemiresistors, including metal-, semiconducting metal oxide-, carbon-based materials, and other materials. The underlying sensing mechanisms for different types of materials are discussed, and the correlation of sensing performances with nanostructures, surface chemistry, and electronic properties is presented. In addition, the discussion of each material emphasizes key advances and strategies to develop superior H2 sensors. Furthermore, recent key advances in other types of H2 sensors are briefly discussed. Finally, the review concludes with a brief outlook, perspective, and future directions.

Chemiresistive Hydrogen Sensors: Fundamentals, Recent Advances, and Challenges.

SnO-SnO2 modified two-dimensional MXene Ti3C2Tx for acetone gas sensor working at room temperature

One-step synthesis of micro-/mesoporous SnO2 spheres by solvothermal method for toluene gas sensor

Extremely stable gas sensors at elevated temperature (T > 400 °C) with rapid detection of hydrogen gas are urgently demanded especially for hydrogen production industry which typically involves a high-temperature system. Gallium nitride (GaN) possesses excellent physicochemical properties and is expected to be one candidate for high temperature gas sensor. In this work, the GaN preparation from α–GaOOH precursors by a direct nitridation method under NH3 flow is presented. The nitridation was done at various temperatures to obtain GaN with different oxygen contents, which played a vital role in gas sensing response of thick film GaN in various concentration of H2 gas at 500 °C. The sensitivity of the obtained GaN with 2.07 wt.% of oxygen content was 10 times higher than that sample with the lowest oxygen content (1.9 wt.%) and the sensitivity drastically decreased when the oxygen content was 2.53 wt.%. The sensors also demonstrated high stability as indicated by their repeatable feature after being exposed at a various concentration of H2 (150–750 ppm). Furthermore, the GaN showed higher sensitivity than that of β–Ga2O3 sensor.

High temperature hydrogen gas sensing property of GaN prepared from Α-GaOOH

A fully integrated, flexible, and functional sensing device for exhaled breath analysis drastically transforms conventional medical diagnosis to non-invasive, low-cost, real-time, and personalized health care. 2D materials based on MXenes offer multiple advantages for accurately detecting various breath biomarkers compared to conventional semiconducting oxides. High surface sensitivity, large surface-to-weight ratio, room temperature detection, and easy-to-assemble structures are vital parameters for such sensing devices in which MXenes have demonstrated all these properties both experimentally and theoretically. So far, MXenes-based flexible sensor is successfully fabricated at a lab-scale and is predicted to be translated into clinical practice within the next few years. This review presents a potential application of MXenes as emerging materials for flexible and wearable sensor devices. The biomarkers from exhaled breath are described first, with emphasis on metabolic processes and diseases indicated by abnormal biomarkers. Then, biomarkers sensing performances provided by MXenes families and the enhancement strategies are discussed. The method of fabrications toward MXenes integration into various flexible substrates is summarized. Finally, the fundamental challenges and prospects, including portable integration with Internet-of-Thing (IoT) and Artificial Intelligence (AI), are addressed to realize marketization.

Angga Hermawan

Papers

CuO Nanoparticles/Ti3C2Tx MXene Hybrid Nanocomposites for Detection of Toluene Gas

SnO-SnO2 modified two-dimensional MXene Ti3C2Tx for acetone gas sensor working at room temperature

One-step synthesis of micro-/mesoporous SnO2 spheres by solvothermal method for toluene gas sensor

High temperature hydrogen gas sensing property of GaN prepared from Α-GaOOH

Prospects and Challenges of MXenes as Emerging Sensing Materials for Flexible and Wearable Breath-Based Biomarker Diagnosis.