Low Enhancement Factor Research Articles

Migration costs and rewarding schemes in spatial public goods games.

This study explores the influence of migration costs and rewarding schemes on cooperation through the implementation of computational behavioral models in spatial public goods games. The former involves a cost for agents to migrate to a neighboring group, while the latter rewards them for remaining in the same group for multiple rounds. By analyzing these mechanisms separately and in combination, we unveil their effects on cooperative behavior. The grid-based game dynamics begins with equal size groups, and agents can adjust their contributions each round, with the option to migrate if unsatisfied. Our findings reveal that when considered separately, the rewarding scheme is not as effective in achieving full cooperation as the migration cost scheme. Combining migration costs and rewards instead yields high cooperation levels with low public goods game enhancement factors and migration probability. Our results offer valuable insights for contexts where promoting cooperative behavior is crucial, such as community engagement development and public policies.

Flower-like Ag-decked non-stoichiometric Bi2O3-x/rGO hybrid nanocomposite SERS substrates for an effective detection of Rhodamine 6G dye molecules.

In early years, SERS-active substrates were generally noble metals. However, their practical applications were limited due to their poor biocompatibility, low uniformity and high cost. Recently, the utilization of semiconductor SERS-active substrates has greatly expanded the applications of SERS in many fields. However, metal-free SERS-active substrates have a low enhancement factor (EF), which can be overcome by adjusting their oxygen deficiency or through the effective preparation of non-stoichiometric semiconducting oxide materials. This is the key strategy and may work as an efficient and simple way to achieve high sensitivity and obtain an enhancement factor (G-factor) comparable to that of noble metals. Here, we report the preparation of flower-like rGO-Bi2O3/Bi2O2.75 and rGO-Ag-Bi2O3/Bi2O2.75 hybrid thin film nanocomposites using a liquid/liquid interface method (LLI) for the first time. In addition to the synergic effect of different enhancement mechanisms, the 3-D flower-like morphology of the substrate shows more favourable properties to improve the G-factor due to the existence of more hotspots. The rGO-Ag-Bi2O3/Bi2O2.75 hybrid thin-film nanocomposites show an EF of 1.8 × 109 with a detection ability of up to 1 nM towards Rhodamine 6G (R6G), which is highly toxic to humans and the aquatic environment.

Two-dimensional silver nanonetwork on Ag4Ti5O12 film as highly efficient SERS substrate

Surface Enhanced Raman Spectroscopy (SERS) is a powerful technique to study and detect single molecules adsorbed onto a surface. In this work, molar concentrations were varied over three consecutive orders of magnitude (10-3 M, 10-6 M, 10-9 M) of Methylene Blue (MB) to study SERS on different thicknesses of silver (6, 8, 10, 12 nm) coated on Ag4Ti5O12 deposited onto glass substrates as the base material. The Ag4Ti5O12 thin films were prepared by a unique ion-exchange method where Li4Ti5O12 thin films were initially deposited by the sol–gel method followed by the exchange of Li+ ion with Ag+ ion. The varied thicknesses of thermally deposited Ag-thin films were grown with unaltered Ag+ ions nucleation sites atop the Ag4Ti5O12 layer to create the two-dimensional (2D) nanonetwork. The structure and morphology of the as-prepared thin-film samples were characterized using X-ray diffraction, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM) techniques. The SERS enhancement factor (EF), calculated using Raman spectroscopy, showed the systematic changes in the Raman signal enhancement as a function of Ag-thickness. The 10 nm thick as-deposited Ag sample showed the highest signal enhancement in Raman spectra than the other Ag thickness films. The successive signal enhancement was obtained due to forming the critical nuclei size of Ag on top of Ag4Ti5O12, which was further bolstered with film surface roughness and surface energy measurements. The as-prepared Ag-10 nm sample showed the lowest film roughness of ∼2.07 nm, in tune with the maximum enhancement factor (EF). We believe this work could open wide opportunities for developing efficient SERS substrates with sensing capabilities for ultra-low analyte concentration coupled with low cost and high enhancement factors.

Optimization of physical vapor deposition process for low background nanoimprinted SERS substrate in quantitative melamine analysis

Uniformity, sensitivity, reproducibility, and cost are the critical parameters of practical surface-enhanced-Raman-spectroscopy (SERS) substrates. Herein, we proposed a High-Aspect-Ratio-Nano-Pillar-Array (HARNPA) substrate deposited silver by physical vapor deposition (PVD) methods (e.g. E-beam evaporation, sputtering, and a two-stage intermittent sputtering) to fabricate high-performance SERS substrates. The substrate by the E-beam evaporation has a significant SERS effect, but the Raman background induced by the exposure of the polymer HARNPA limits the analyte choice. The substrate by the sputtering method has better step coverage of silver but a lower enhancement factor. Therefore, we proposed a process of two-stage intermittent sputtering to solve these limitations. In addition, we define a factor called the signal-to-background peak ratio (S/B peak ratio) to evaluate the influence of the Raman background from the SERS substrate. Finally, we accomplished a SERS substrate with an S/B peak ratio of 3.48 by intermittent sputtering, which has the best linearity (R2 = 0.97) of the melamine concentration curve and the lowest detection limit (LoD = 5.6 × 10-7 M) that meets the regulatory requirements for melamine detection (3.96 × 10-6 M). The benefits of our SERS substrates are easy fabrication, high sensitivity (EF = 1.44 × 107), high reproducibility (CV = 8.4 %), and excellent uniformity (CV = 7 % in 4″ area), which are beneficial for mass production in the future.

Evolution of cooperation with tag-based expulsion in spatial public goods game

We introduce tag-based expulsion and explore its dynamic influence on cooperative behavior within a spatial public goods game. Our model employs a multi-agent system where agents, characterized by their strategies and tags, participate in public goods games and expel neighbors with dissimilar tags. The expulsion process effectively reshapes the interaction structure, providing a protective shield for cooperative clusters against defector infiltration. We demonstrate that expulsion, tag mutability, and tolerance are pivotal in driving cooperation levels and the optimal interaction structure. Even in less favorable conditions characterized by low enhancement factors, cooperation can emerge given appropriate tolerance levels. Our research underscores the importance of moderate population density, tag-based expulsion, and well-calibrated expulsion intensity in fostering cooperation, introducing fresh perspectives on the interplay between social dynamics and evolutionary processes. Additionally, we provide evidence of the dynamic adaptability of expulsion mechanisms, suggesting they may be integral to understanding cooperation in various societal contexts. These findings open up new avenues for further exploration of the complexity of cooperative behaviors and the roles of expulsion mechanisms in the evolution of cooperation.

Continuous Spatial Public Goods Game Based on Particle Swarm Optimization with Memory Stability

Public goods games have been extensively studied to determine the mechanism behind cooperation in social dilemmas. Previous public goods games based on particle swarm algorithms enabled individuals to integrate their past best strategies with the current best strategies of their neighbors, which can effectively promote cooperation. In this paper, we introduce the concept of memory stability and explore the effects of different memory stability coefficients on strategy distribution, strategy update rate, and average cooperation level. Our simulation results showed that, in the case of a very high propensity coefficient, infinite memory stability coefficients cannot reach a high level of cooperation, while reducing memory stability can reach a very high level of cooperation. At a low enhancement factor, weakening memory stability decreased the average cooperation level, while at a higher enhancement factor, a weakening memory stability greatly increased the average group cooperation level. Our study provides new insights into the application of particle swarm algorithms to public goods games.

Gold nanoparticles are capped under the IRMOF-3 platform for in-situ surface-enhanced Raman scattering technique and optic fiber sensor

Integrating noble-metal and organic-inorganic hybrid crystalline porous materials for Raman signal augmentation is crucial for surface-enhance Raman spectroscopy. This study effectively generated gold nanoparticles / metal-organic frameworks (Au NPs/IRMOF-3) hybrids. The activity of Au NPs/IRMOF-3 double component substrate was significantly enhanced under localized surface plasmon resonance (LSPR) because the hot electrons produced on Au NPs surface were incorporated with IRMOF-3 and utilized the porous structure to capture the analyte. Development much hot spots of great significance for surface-enhanced Raman scattering (SERS) technique, herein, we developed an Au NPs/IRMOF-3-based nanosensor for rhodamine B (RhB) sensing by using in-situ SERS technique. X-ray diffraction (XRD) spectrometry, surface morphology analysis, optical properties, and energy-dispersive X-ray (EDX) spectroscopy were used to examine the layer-by-layer deposited substrate. The Au NPs/IRMOF-3 multilayers generated chemical and electromagnetic amplification of Raman signals of Rhodamine B at a low concentration and high enhancement factor. In the presence of dopamine molecules, due to the strong specific affinity between the modified surface out-layer of fiber sensor and the target molecules, resulting in the obvious change of the optical power transmission signals, which can be used for dopamine sensing with high sensitivity and stability (limit of detection is 1.42 × 10 -18 M with a wide linear range from 10 -17 to 6 × 10 -8 M of dopamine). The Au NPs/IRMOF-3 nanosensor can be used as an ideal platform for real applications, especially for some gases or low-weight molecules in the future. • Using a traditional synthesis approach, low cost, and high synthesis efficiency. • This sensor has high homogeneity and a stable arrangement structure. • Determination of Rhodamine B at low detection limit of 10 -9 M along with an enhancement factor of 6.54 × 10 9 . • Limit of detection is 1.42 × 10 -18 M and measurement range with a linear response from 10 −17 to 10 −8 M.

Influence on SERS enhancement factor of the components of an artificial opal loaded with metal NPs: A systematic study

We have inquired about the influence of composite artificial opal components on its SERS enhancement factor (EF). Particularly, we considered metal (100 nm) and dielectric spheres (290 nm), and an excitation wavelength of 632 nm. We show that the electric field of a SiO2 sphere is weaker and more uniform as its porosity increases. Additionally, a porous sphere promotes a lower EF compared to that of a non-porous sphere. The optical response of the composite opal is insensitive to the polarization state of the incident field. A SERS EF of 104 is reachable with an opal loaded with Au or Ag NPs. In general, the dielectric spheres affect the SERS EF intensity of the metal NPs. From the optical spectra, we observed that with a 632 nm wavelength, the composite opal is out of resonance.

Designed 3D N-doped magnetic porous carbon spheres for sensitive monitoring of biogenic amine by simultaneous microwave-assisted derivatization and magnetic-solid phase extraction

In this paper, the novel 3D N-doped magnetic porous carbon spheres (3D N-MPCSs) was constructed via a simple template-free and self-doping method, followed by a direct carbonization of polymer with Fe3+ for simultaneous activation and magnetization. For the first time, the designed 3D N-MPCSs was used as multifunctional (for extraction and magnetic separation) adsorbents for microwave-assisted derivatization and magnetic solid phase extraction, which exhibited excellent extraction ability for its large surface area, mesoporous structure, spherical morphology, and incorporation of N/O heteroatoms. Moreover, when the microwave-assisted derivatization was combined with the magnetic solid phase extraction, the extraction, derivatization and concentration was completed simultaneously within 135 s. Furthermore, this method has a low detection limit (0.059–0.073 ng mL−1) and high enhancement factors (333 < EFs < 382) for trace biogenic amine (BAs). The recoveries were between 92.3 and 108.8% with relative standard deviations less than 5.9%. Overall, a simple, rapid, efficient and sensitive method for the analysis of BAs in food samples was developed, which provided the basis for routine detection of food safety.

Ultrasensitive Sensing of Volatile Organic Compounds Using a Cu-Doped SnO2 -NiO p-n Heterostructure That Shows Significant Raman Enhancement*.

Surface enhanced Raman scattering (SERS) based on chemical mechanism (CM) attracts tremendous attention for great selectivity and stability. However, low enhancement factor (EF) limits its practical applications for trace detection. Here, a novel sponge-like Cu-doping SnO2 -NiO p-n semiconductor heterostructure (SnO2 -NiOx /Cu), was first created as a CM-based SERS substrate with a significant EF of 1.46×1010 . This remarkable EF was mainly attributed to the enhanced charge-separation efficacy of p-n heterojunction and charge transfer resonance resulted from Cu doping. Moreover, the porous structure enriched the probe molecules, resulting in further SERS signals magnification. By immobilizing CuPc as an inner-reference element, SnO2 -NiOx /Cu was developed as a SERS nose for selective recognition of multiple lung cancer related VOCs down to ppb level. The information of VOCs was recorded in a barcode, demonstrating practical potential of a desktop SERS device for biomarker screening.

Ultrasensitive Sensing of Volatile Organic Compounds Using a Cu‐Doped SnO2‐NiO p‐n Heterostructure That Shows Significant Raman Enhancement**

AbstractSurface enhanced Raman scattering (SERS) based on chemical mechanism (CM) attracts tremendous attention for great selectivity and stability. However, low enhancement factor (EF) limits its practical applications for trace detection. Here, a novel sponge‐like Cu‐doping SnO2‐NiO p‐n semiconductor heterostructure (SnO2‐NiOx/Cu), was first created as a CM‐based SERS substrate with a significant EF of 1.46×1010. This remarkable EF was mainly attributed to the enhanced charge‐separation efficacy of p‐n heterojunction and charge transfer resonance resulted from Cu doping. Moreover, the porous structure enriched the probe molecules, resulting in further SERS signals magnification. By immobilizing CuPc as an inner‐reference element, SnO2‐NiOx/Cu was developed as a SERS nose for selective recognition of multiple lung cancer related VOCs down to ppb level. The information of VOCs was recorded in a barcode, demonstrating practical potential of a desktop SERS device for biomarker screening.

Thermal effects in field electron emission from idealized arrangements of independent and interacting micro-protrusions

Modelling studies of thermo-field electron emission (TFE) from protrusions at a cathode surface usually use simulations in 2D axial symmetry. Indeed, time-dependent simulations in 3D are very demanding in computation time. Often, 3D simulations have been restricted to stationary pure field electron emission to account for the drastic current decrease caused by electric field screening when the emitters are close. Little interest has therefore been granted to the heat exchanges occurring between nearby emitters. Although the temperature is a second-order parameter in TFE compared to the electric field, thermal effects become non-negligible in high current density regimes, where self-heating is well established. The present study focuses on the thermal effects occurring during the TFE from micro-protrusions. Our model considers a DC voltage but solves in time the temperature evolution coupling the heat equation and the current continuity equation. The protrusions are modelled as hemiellipsoids with 2D axial symmetry. Emission enhancement due to the increase of the temperature in the thermo-field regime compared to the pure field regime is detailed as a test case for isolated protrusions. Then, full 3D simulations are used to investigate the thermal coupling between multiple neighbouring protrusions via their outwards heat fluxes inside the cathode. The results show a higher current increase due to thermal coupling for dome-like protrusions with a low field enhancement factor. The current increases up to 13% of the total current for aspect ratios of 1, but this value is reached for an extreme applied electric field, hardly reachable in experiments. For sharper protrusions with higher field enhancement, the interaction range through the cathode being shorter, the thermal coupling is suppressed by electrostatic screening. Nevertheless, in arrangements of densely distributed field emitter, when the screening is compensated by a higher voltage, our model predicts the possibility of a moderate but noticeable thermal coupling even for sharp protrusions: a parametric study indicates up to 14.5% of the emitted current being caused by a thermal coupling through the cathode bulk, for protrusions with an aspect ratio of 10 under a fixed applied electric field of 0.4 GV m−1 in DC mode.

Low-carbon technology collaborative innovation in industrial cluster with social exclusion: An evolutionary game theory perspective.

As governments implement low-carbon economy widely, boosting low-carbon transformation in industrial clusters has become a challenge. This study establishes an evolutionary game model of low-carbon technology collaborative innovation based on spatial public goods game to solve the free-riding problem effectively in research and development. By introducing a social exclusion mechanism, we explore the requirements for the emergence of cooperation between enterprises, and we consider the heterogeneity and scale-free characteristics of industrial clusters comprehensively. Simulation results confirm that social exclusion can significantly promote cooperation as a form of cooperation with additional cost. When exclusion cost decreases and probability increases, an excluder can survive in a lower enhancement factor, which guarantees a stable exclusion mechanism. Furthermore, this mechanism is key to forming and maintaining cooperative behavior. When a cluster follows a scale-free distribution, the sparse network structure can avoid cooperation collapse. Moreover, heterogeneous investment is a robust alternative in the face of invading defectors. This study provides a new understanding to promote the collaborative innovation of enterprises in industrial clusters.

Frequency-resolved photothermal lens: An alternative approach for thermal diffusivity measurements in weak absorbing thin samples

In this work, a pump-probe frequency-resolved photothermal lens method, for measuring thermal diffusivity, has been presented. The method is based on measurement of induced thermal lens signal amplitude as a function of time taken from different modulation frequencies of the pump beam. The performance of the technique was verified by determination of thermal diffusivity of four standard weak absorbing reference thin samples such as: ethanol, water, soda-lime-glass and polymethylmethacrylate and comparing the results to thermal diffusivities reported by other conventional photothermal methods.Good agreement among the obtained results and reported literature values confirmed that the method is a reliable and accurate technique applicable for determination of thermal diffusivity of weak absorbing thin materials. Furthermore, the use of lock-in capabilities enables to achieve amplified noise-free signal using few mW of excitation power leading to favourable precision of determination (2%). Moreover, in measurements of samples with very low thermo-optical enhancement factor, the method offers higher sensitivity than conventional photothermal technique. Additionally, lowest power threshold for measuring thermal parameters is crucial for thin films as well as for photodegradable samples, making it an important advantage of the method.

Tailoring carbon for single molecule detection – Broad spectrum 3D quantum sensor

Current single-molecule SERS sensing is mostly done by plasmonic materials like Gold and Silver due to higher enhancement efficiency. However, plasmonic materials suffer from inherent disadvantages, including inconsistent spectral signature and non-biocompatibility. Researchers are actively searching for a replacement with superior biocompatibility and a uniform spectral signature. Quantum scale Graphene-based SERS signifies a newfound frontier in this regard, owing to high surface area and tunable optical and electronic properties. The use of GQD as a SERS sensor is still critically impeded by low enhancement factor as well as inferior sensitivity due to wavelength-dependent fluorescence property. In this work, we introduce a 3-D Graphene Oxide Quantum sensor (GOQS) with an unmatched enhancement of 1014, enabling ultra-sensitive detection with a limit of detection down to single molecule sensitivity. With 3-D architecture, the interference of the inherent fluorescence of GQD is eliminated, thereby achieving a relatively high enhancement factor on par with plasmonic materials. The high enhancement factor is a combined effect of quantum confinement, edge effects, and charge transfer through molecular adsorption. The single molecule sensitivity (10 −15 M) was experimentally verified using a Raman Probe molecule (CV, R6 G) with excellent repeatability. As a distinct confirmation of single molecule sensitivity of GOQS, we have detected two Raman probe molecules (CV, R6 G) simultaneously, thereby systematically computing the probability of detecting at 10 -15 M level. The ability to detect and distinguish Raman probe molecules simultaneously down to femtomolar level is the lowest limit of detection reported in a non-plasmonic sensor thus far. GOQS was demonstrated for the detecting of disease biomarkers and using Tryptophan. An environmental contaminant Bisphenol-A was detected at a concentration of 10−15 M, corresponding to 2000 ppb. The experimental results indicate a new paradigm towards the activation of quantum scale graphene as a broad-spectrum SERS sensor for numerous ultra-trace analysis.

Plasmon-Free Surface-Enhanced Raman Spectroscopy Using Metallic 2D Materials

Two dimensional (2D) materials-based plasmon-free surface-enhanced Raman scattering (SERS) is an emerging field in nondestructive analysis. However, impeded by the low density of state (DOS), an inferior detection sensitivity is frequently encountered due to the low enhancement factor of most 2D materials. Metallic transition-metal dichalcogenides (TMDs) could be ideal plasmon-free SERS substrates because of their abundant DOS near the Fermi level. However, the absence of controllable synthesis of metallic 2D TMDs has hindered their study as SERS substrates. Here, we realize controllable synthesis of ultrathin metallic 2D niobium disulfide (NbS2) (<2.5 nm) with large domain size (>160 μm). We have explored the SERS performance of as-obtained NbS2, which shows a detection limit down to 10-14 mol·L-1. The enhancement mechanism was studied in depth by density functional theory, which suggested a strong correlation between the SERS performance and DOS near the Fermi level. NbS2 features the most abundant DOS and strongest binding energy with probe molecules as compared with other 2D materials such as graphene, 1T-phase MoS2, and 2H-phase MoS2. The large DOS increases the intermolecular charge transfer probability and thus induces prominent Raman enhancement. To extend the results to practical applications, the resulting NbS2-based plasmon-free SERS substrates were applied for distinguishing different types of red wines.

A rapidly converging initialisation method to simulate the present-day Greenland ice sheet using the GRISLI ice sheet model (version 1.3)

Abstract. Providing reliable projections of the ice sheet contribution to future sea-level rise has become one of the main challenges of the ice sheet modelling community. To increase confidence in future projections, a good knowledge of the present-day state of ice flow dynamics, which is critically dependent on basal conditions, is strongly needed. The main difficulty is tied to the scarcity of observations at the ice–bed interface at the scale of the whole ice sheet, resulting in poorly constrained parameterisations in ice sheet models. To circumvent this drawback, inverse modelling approaches can be developed to infer initial conditions for ice sheet models that best reproduce available data. Most often such approaches allow for a good representation of the mean present-day state of the ice sheet but are accompanied with unphysical trends. Here, we present an initialisation method for the Greenland ice sheet using the thermo-mechanical hybrid GRISLI (GRenoble Ice Shelf and Land Ice) ice sheet model. Our approach is based on the adjustment of the basal drag coefficient that relates the sliding velocities at the ice–bed interface to basal shear stress in unfrozen bed areas. This method relies on an iterative process in which the basal drag is periodically adjusted in such a way that the simulated ice thickness matches the observed one. The quality of the method is assessed by computing the root mean square errors in ice thickness changes. Because the method is based on an adjustment of the sliding velocities only, the results are discussed in terms of varying ice flow enhancement factors that control the deformation rates. We show that this factor has a strong impact on the minimisation of ice thickness errors and has to be chosen as a function of the internal thermal state of the ice sheet (e.g. a low enhancement factor for a warm ice sheet). While the method performance slightly increases with the duration of the minimisation procedure, an ice thickness root mean square error (RMSE) of 50.3 m is obtained in only 1320 model years. This highlights a rapid convergence and demonstrates that the method can be used for computationally expensive ice sheet models.

TiN-nanorod-coated carbon fiber cathode for high-current-density electron emission

The challenges confronting high-current cold cathodes stimulate the development of robust cathode materials with low emission threshold and high field enhancement factor. In this paper, we prepared a TiN nanorod/carbon fiber composite cathode by hydrothermal method and nitriding. The light emission and plasma formation on the cathode surface were compared between carbon fiber cathode and TiN nanorod/cabon fiber cathode. The turn-on times of TiN nanorod/cabon fiber cathode and carbon fiber cathode were 12 ns and 31 ns, respectively, showing a faster turn-on of TiN nanorod/cabon fiber cathode, which was supported by theoretical derivation, developing process of emission area and IV Characteristics. The emission thresholds of TiN nanorod/cabon fiber cathode and carbon fiber cathode were around 0.4 kV/cm and 0.8 kV/cm, respectively, and such a lower emission threshold of TiN nanorod/cabon fiber cathode enables the uniform and large-area plasma generated on cathode surface. As a whole, TiN nanorod/cabon fiber cathode represents a promising cold cathode with superior performances.

Effects of enhancement level on evolutionary public goods game with payoff aspirations

In this work, we study the spatial evolutionary public goods game by introducing payoff aspirations for players, and players update their strategies with a stochastic probability depending on the difference between their collecting payoffs from neighbors and own payoff aspirations. A striking finding is that the cooperation level is a nonmonotonic function of the enhancement factor for a fixed aspiration level, which means a proper enhancement factor leads to the optimal cooperation level, whereas too high or too low enhancement factors will impede the evolution of cooperation for a particular aspiration level. This phenomenon is contradictory to the previous finding that a larger enhancement factor always leads a higher cooperation level. We explain this anomaly with a comprehensive analysis of the probabilities transitions of C players to D players as well as the reverse. The presented results may be not only helpful in understanding the cooperative behavior induced by the aspiration level in economic or animal society, but also have important implications for the cooperation regulation in system by enhancement factors and payoff aspirations.

Single sea urchin-MoO3 nanostructure for surface enhanced Raman spectroscopy of dyes.

Enhancing the surface-enhanced Raman scattering (SERS) activity of semiconductor metal oxide nanostructures by controlling the morphology and oxygen vacancies towards trace detection of organics is of significant interest. In this study, MoO3 with a novel sea urchin morphology is synthesized employing chemical bath deposition and consists of hundreds of ∼15 μm long spikes originating from the core forming 20–40 micron globular structures. The spikes taper to form 20 nm sharp tips. SERS of rhodamine 6G (R6G) over MoO3 sea urchins has been investigated and compared to that of 1D h-MoO3 nanorod arrays. The SERS activity is morphology dependent and the sea urchin-like morphology exhibits higher SERS activity with an enhancement factor (EF) of the order 105 and a detection limit of 100 nM, while for h-MoO3 nanorods, the corresponding values are 103 and 1 μM, respectively. X-ray photoelectron spectroscopy reveals a high concentration of Mo+5 states in sea urchins indicating lattice oxygen vacancies. The observed EF is quite high for a metal oxide substrate and is attributed to the enhanced charge transfer between analyte molecules and the substrate promoted by the oxygen vacancies along with surface defects and hydroxyl groups on MoO3 sea urchins providing more active sites for the adsorption of probe molecules. The role of oxygen vacancies is confirmed by the lower EF value exhibited by the stoichiometric 1D h-MoO3. Raman mapping of a single sea urchin is achieved with good R6G intensity and indicates that the tips of spiky features are involved in SERS enhancement. The reusability of substrates is shown for repeated cycles of R6G adsorption by UV irradiation exploiting the photocatalytic activity of MoO3 nanostructures.