Gas sensing technology is crucial for a wide variety of applications [1]. Currently, traditional gas sensing materials are hindered by limitations in selectively detecting single-type gas due to the non-specific interactions between gas molecules and sensing materials [2,3]. Single atoms (SAs) have the potential to generate specific effects on a single-type gas due to the uniform active center configuration [4,5]. However, the means to stimulate the capacity of single atoms towards a single-type gas sensing are still lacking. Therefore, the design of highly sensitive and selective sensing single-atom materials for single-type gas detection needs more attention. Recently, by utilizing the dynamic changes in the coordination structure of cobalt single atoms, Wu and Feng et al. realized high sensitivity and high selectivity towards ammonia gas sensing. In this work, they developed a cobalt single-atom material with a bidentate coordination structure (Co-2MI-G), which exhibited ultra-high selectivity for NH3 sensing [6]. A high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) image showed that no aggregates were formed on the surface of graphene-like Co-2MI-G and the Co single atoms were uniformly dispersed (Fig. 1a). It is indicated that from the fitting of Fourier transformed-extended X-ray absorption fine structure (FT-EXAFS), the coordination number of Co single atoms changed from 2 in pristine Co-2MI-G to 4 after NH3 gas exposure, corresponding to a stable model of bonding with two NH3 molecules (Fig. 1b and c). In order to further clarify the special coordination evolution mechanism, quasi in-situ X-ray photoelectron spectroscopy (XPS) technology was used to explore the state changes of Co single atoms before and after exposure to NH3. As illustrated in Fig. 1d, the satellite peak intensity for Co 2p decreased significantly, while the 2p1/2–2p3/2 separation energy weakened, indicating the conversion of Co2+ to Co3+. As a result, the Co-2MI-G-based sensor showed ultra-high sensitivity (67.598% for 1 ppm NH3, Fig. 1e) and high selectivity for volatile organic compounds (VOCs) and other interfering gases (Fig. 1f). Theoretical simulation elucidated the chemisorption process of NH3 molecules on Co-2MI-G. Density of state (DOS) analysis indicated that the Co-2MI-G adsorbed with NH3 displayed a stronger insulation and higher oxidation state than pristine Co-2MI-G, which enlarged the band gap from 0.14 eV to 0.50 eV (Fig. 1g). (a) HAADF-STEM image of Co-2MI-G. (b, c) FT-EXAFS curves of the proposed structure and the measured Co-2MI-G and Co-2MI-G + NH3. Insets are the proposed model of Co-2MI-G and Co-2MI-G + NH3 architectures. (d) Quasi in-situ XPS spectra of Co-2MI-G before and after exposure to NH3, followed by NH3 evaporation. (e) The resistance response curves of the Co-2MI-G-based sensor. (f) Selectivity of Co-2MI-G to NH3 and other VOCs gases. (g) Demonstration of frontier molecular orbital structures of Co-2MI-G and Co-2MI-G + 2NH3. Reproduced from ref. [6] with permission. In summary, this paper verifies that single atoms with a dynamically changing coordination structure could be used as a single-type gas sensing material with superior sensitivity and selectivity. This work pioneers a novel application of single atoms to the field of single-type gas sensing and provides an innovative perspective on utilizing single atoms by dynamic coordination structure. Conflict of interest statement. None declared.
Gas sensing technology is crucial for a wide variety of applications [1]. Currently, traditional gas sensing materials are hindered by limitations in selectively detecting single-type gas due to the non-specific interactions between gas molecules and sensing materials [2,3]. Single atoms (SAs) have the potential to generate specific effects on a single-type gas due to the uniform active center configuration [4,5]. However, the means to stimulate the capacity of single atoms towards a single-type gas sensing are still lacking. Therefore, the design of highly sensitive and selective sensing single-atom materials for single-type gas detection needs more attention. Recently, by utilizing the dynamic changes in the coordination structure of cobalt single atoms, Wu and Feng et al. realized high sensitivity and high selectivity towards ammonia gas sensing. In this work, they developed a cobalt single-atom material with a bidentate coordination structure (Co-2MI-G), which exhibited ultra-high selectivity for NH3 sensing [6]. A high-angle annular darkfield scanning transmission electron microscopy (HAADF-STEM) image showed that no aggregates were formed on the surface of graphene-like Co-2MI-G and the Co single atoms were uniformly dispersed (Fig. 1a). It is indicated that from the fitting of Fourier transformed-extended X-ray absorption fine structure (FT-EXAFS), the coordination number of Co single atoms changed from 2 in pristine Co-2MI-G to 4 after NH3 gas exposure, corresponding to a stable model of bonding with two NH3 molecules (Fig. 1b and c). In order to further clarify the special coordination evolution mechanism, quasi in-situ X-ray photoelectron spectroscopy (XPS) technology was used to explore the state changes of Co single atoms before and after exposure to NH3. As illustrated in Fig. 1d, the satellite peak intensity for Co 2p decreased significantly, while the 2p1/2–2p3/2 separation energy weakened, indicating the conversion of Co2+ to Co3+. As a result, the Co-2MI-G-based sensor showed ultra-high sensitivity (67.598% for 1 ppm NH3, Fig. 1e) and high selectivity for volatile organic compounds (VOCs) and other interfering gases (Fig. 1f). Theoretical simulation elucidated the chemisorption process of NH3 molecules on Co-2MI-G. Density of state (DOS) analysis indicated that the Co-2MI-G adsorbed with NH3 displayed a stronger insulation and higher oxidation state than pristine Co-2MI-G, which enlarged the band gap from 0.14 eV to 0.50 eV (Fig. 1g). (a) HAADF-STEM image of Co-2MI-G. (b, c) FT-EXAFS curves of the proposed structure and the measured Co-2MI-G and Co-2MI-G + NH3. Insets are the proposed model of Co-2MI-G and Co-2MI-G + NH3 architectures. (d) Quasi in-situ XPS spectra of Co-2MI-G before and after exposure to NH3, followed by NH3 evaporation. (e) The resistance response curves of the Co-2MI-G-based sensor. (f) Selectivity of Co-2MI-G to NH3 and other VOCs gases. (g) Demonstration of frontier molecular orbital structures of Co-2MI-G and Co-2MI-G + 2NH3. Reproduced from ref. [6] with permission. In summary, this paper verifies that single atoms with a dynamically changing coordination structure could be used as a single-type gas sensing material with superior sensitivity and selectivity. This work pioneers a novel application of single atoms to the field of single-type gas sensing and provides an innovative perspective on utilizing single atoms by dynamic coordination structure. Conflict of interest statement. None declared.
Air quality control is an important task in prevention of human exposure to toxic and harmful gases and requires reliable gas sensors. During last decades many gas sensing mechanisms, based on different physical or chemical interactions with sensitive materials, have been developed, but the problem of precise analysis of gas mixtures still remains. The problem can be solved by introducing new sensing mechanism based on an adiabatically changing electric field interacting with the rotational structure of the molecules with dipole moments. We have theoretically demonstrated a single low frequency gas detector that can be used for sensing of gas mixtures with high selectivity, accuracy, and sensitivity. The enhancement of the population difference between corresponding molecular levels and reached the theoretical maximum of absorption have been shown.
During last decades many gas sensing mechanisms, based on different physical or chemical interactions with sensitive materials, have been developed, but the problem of precise analysis of gas mixtures still remains. New sensing mechanism has been suggested that is based on an adiabatically changing electric field interacting with the rotational structure of the molecules with dipole moments. A single low frequency gas detector, that can be used for sensing of gas mixtures with high selectivity, accuracy, and sensitivity, has been theoretically demonstrated. The enhancement of the population difference between corresponding molecular levels and reached the theoretical maximum of absorption have been shown.
The energy sector has become increasingly dependent upon highly sensitive sensing devices for a wide range of applications. Variables such as temperature, pH, electromagnetic fields, ions, and pressure must be measured with high precision, often in harsh conditions (e.g. highly corrosive environments due to high temperature, pressure and humidity). These sensors are deployed in infrastructure such as transformers, pipelines, mines, nuclear power plants, and other areas to ensure safe operating conditions and uninterrupted, optimized service. Moreover, new opportunities for sensors have emerged due to the expansion of smart grids/meters, driverless vehicles, and the discovery of new oil, gas, and critical mineral deposits. The continued maturation of quantum sensing technologies offers exciting opportunities for quantum-enhanced measurements within the energy sector that may provide significant improvements in sensitivity beyond the classical limit. Here, an overview of established and emerging quantum materials for sensing applications will be provided, from trapped ions to color centers in diamond and silicon carbide. Associated quantum sensing methods for these materials will be discussed, with an emphasis on platforms that are nearing commercial viability. Specific application opportunities within the energy sector for quantum sensors will then be analyzed, including oil/gas discovery, greenhouse gas emission monitoring, pH and ion sensing, current measurement in electric vehicle batteries, and quantum-enhanced spectroscopy. Remaining barriers, such as quantum sensor platform miniaturization and ruggedization, will also be analyzed. A specific project at the National Energy Technology Laboratory involving the functionalization of qubits using metal-organic frameworks for enhanced quantum sensing will also be highlighted. Here, nitrogen vacancy centers (NV) in nanodiamonds, a commercially available qubit with long coherence times and utilizable quantum properties at room temperature, are encapsulated in a controlled way using the metal-organic framework ZIF-8. The ZIF-8 provides a well-defined, porous scaffold that can be controlled to promote the selective uptake of specific target analytes, such as gas molecules or ions. The quantum sensing performance of this composite material is either preserved or enhanced following ZIF-8 encapsulation; the optically detected magnetic resonance response of the NV nanodiamonds with and without the ZIF-8 coating are identical, while the ZIF-8 coating increases the longitudinal spin relaxation lifetime (T1) of the NV centers, an important parameter for spin relaxometry-based quantum sensing experiments. Taken together, these results demonstrate the importance of qubit functionalization as a crucial step for rationally designing high performance quantum sensors.
Ultracold Fermi gases provide versatile and flexible settings for molecular interactions and reaction dynamics in quantum regimes. Recently, Lianghui Huang and colleagues created weakly bound Feshbach molecules from the two spin components of 40K atomic Fermi gas. They then investigated the radio-frequency (RF) spectra of the weakly bound molecules and from that obtained the magnetic-field-dependent binding energy. The RF dissociation spectroscopy of the weakly bound molecules could be used to study ultracold molecule–molecule and molecule–atom collisions in the presence or absence of spin–orbit coupling. [Chin Phys B, 2014; 23(1): 013402] Researchers Guanjun Wang and colleagues have constructed a new apparatus based on a collinear tandem time-of-flight mass spectrometer to measure infrared photodissociation spectroscopy of size-selected ions in the gas phase. A simple new assembly, integrated with a mass gate and deceleration and reacceleration ion optics, was designed to fulfill mass selection, infrared photodissociation and fragment and parent ion mass analysis. Such an experimental setup provides a powerful tool to measure the infrared spectra of size-selected ions in the gas phase with high sensitivity. [Sci China Chem, 2013; 56(10): 1–6] Schematic diagram of the experimental apparatus consisting of a laser vaporization supersonic ion source and a collinear tandem time-of-flight mass spectrometer for infrared photodissociation spectroscopy. Published in Sci China-Chem, 2013; 56(10): 1–6. Gravitational potential energy sources and sinks, associated with different oceanic model parameterizations, can be used as criteria in evaluating the performance of a model. The upper bound of energy associated with lateral diffusion or advection is estimated at 100 GW. Any parameterizations associated with energy larger than the bound energy are unphysical. Further, any energy sources resulting from cabbeling associated with lateral advection in the Eulerian coordinate are artificial. In particular, huge sources or sinks in the widely used sigma-coordinated models imply the unphysical nature of such parameterization. [Acta Oceanol Sin, 2014; 33(3): 1–18] Graphene, composed of a single sheet of carbon atoms, has the potential for use in numerous exciting applications. Realizing its potential, however, requires sophisticated large-scale fabrication techniques that do not leave any residue on the graphene surface. By incorporating a protective metal layer into the standard photolithographic process, Johnson et al. have fabricated large-scale arrays of chemical vapor sensors. Specifically, the arrays are based on graphene field-effect transistors that are functionalized with DNA. These chemically functionalized graphene transistors act as a highly sensitive ‘electronic nose’, capable of detecting organic compounds at very low levels (parts per billion). [Nano Res, 2014; 7(1): 95–103]
Atomically thin two-dimensional materials, with their ultra-thin structure and exceptional sensitivity to the local environment, are emerging as an important platform for next-generation quantum sensing. Their van der Waals bonding and atomic thin layers allow sensing elements to be placed in extremely close proximity to target systems—often just a few atoms away. This proximity dramatically enhances interactions with local optical, mechanical, and electrostatic fields, enabling exceptionally sensitive detection with ultrahigh spatial resolution. Beyond sensitivity, the layered van der Waals architecture offers a unique opportunity to integrate multiple sensing functions into a unified platform, where sensing, signal amplification, and readout can be distributed across tailored layers rather than relying on a single sensor element. Recent advances in optically addressable spin defects in hexagonal boron nitride and excitonic and polaritonic platforms in transition-metal dichalcogenides highlight the emergence of a new generation of quantum and quantum-enhanced sensors. These sensors conform to various substrates and enable multiparameter detection. In this Perspective, we outline the principles that distinguish atomically thin quantum sensors from bulk counterparts and explore emerging opportunities and challenges in developing scalable, multifunctional 2D quantum sensing technologies.
Molecular quantum sensors represent a promising frontier for the detection of nuclear magnetic resonance signals and alternating current magnetic fields at the nanoscale, potentially reaching single-proton sensitivity. Although the triplet states of molecular pentacene provide a viable sensing architecture, the triplet pair states produced by singlet fission of pentacene dimers could enable more flexible quantum manipulations through entanglement. In this work, we model the quantum sensing efficacy of a spin-polarized quintet manifold in a photoexcited pentacene dimer generated via intramolecular singlet fission. Using a Lindblad master equation approach, we simulate the evolution of the triplet pair state under standard dynamical decoupling sequences, including spin echo, XY4, and XY8 and provide a direct performance comparison to the traditional pentacene monomer benchmark. While both architectures exhibit comparable sensitivity for isolated single-spin detection, our findings indicate that the dimer architecture provides a superior interaction cross-section for detecting small ensembles of nuclear spins. Analytical expressions derived for fluorescence modulation demonstrate that sensitivity is optimized in the low-magnetic field regime and scales with the number of pulses in the sensing protocol. This study establishes a theoretical baseline for utilizing high-spin multi-excitonic states as chemically tunable, high-sensitivity quantum probes.