Search Results (15)

Cu-based nanomaterials have received considerable attention as promising and cost-effective substrates for surface-enhanced Raman spectroscopy (SERS) applications despite their relatively low enhancement factor (EF) compared to noble metals like gold and silver. In this study, a fast and affordable synthesis route is proposed to obtain a three-dimensional porous copper film (NPC) via an electrodeposition technique based on the dynamic hydrogen bubbling template (DHBT). Two sets of NPC film were synthesized, one without additives and the other with cetyltrimethylammonium bromide (CTAB). The impacts of deposition time on the NPCs’ porous morphology, thickness, and SERS performance were systematically investigated. With the optimal deposition time, the nanopore sizes could be tailored from 26.8 to 73 μm without additives and from 12.8 to 24 µm in the presence of CTAB. The optimal additive-free NPC film demonstrated excellent SERS performance at 180 s of deposition, while the CTAB-modified film showed strong enhancement at 120 s towards methylene blue (MB), a highly toxic dye, achieving a detection limit of 10⁻⁶ M. Additionally, the samples with CTAB showed better efficiency than those without CTAB. The calculated EF of NPC was found to be 5.9 × 10³ without CTAB and 2.5 × 10³ with the CTAB, indicating the potential of NPC as a cost-effective candidate for high-performance SERS substrates. This comprehensive study provides insights into optimizing the structural morphology of the NPCs to maximize their SERS enhancement factor and improve their detection sensitivity toward MB, thus overcoming the limitations associated with conventional copper-based SERS substrates. Full article

CO₂ electrochemical reduction is a promising way to convert CO₂ to valuable fuels and chemicals. This study presents a porous Cu@Zn foam catalyst with a tailored hydrophobic surface for enhanced CO₂ reduction. The catalyst is synthesized via a modified dynamic hydrogen bubble template method, incorporating polytetrafluoroethylene (PTFE) during electrodeposition to control wettability. This strategy creates a hydrophobic microenvironment that significantly increases the three-phase (gas–liquid–solid) contact area, promoting CO₂ mass transfer and suppressing the competing hydrogen evolution reaction. The optimized Cu@Zn-8PTFE catalyst achieves a CO Faraday efficiency (FE_CO) of 87.53% at −35 mA cm⁻², a 40% improvement over the unmodified Cu@Zn. Furthermore, it also exhibits excellent stability, maintaining FE_CO > 90% for 64 h at −15 mA cm⁻². While hydrophobic modification is beneficial, excess PTFE loading reduces performance by covering active sites and diminishing the three-phase interface. This work highlights the importance of controlling catalyst wettability to optimize the three-phase interface for enhanced CO₂ electroreduction. Full article

In this study, a three-dimensional (3D) interconnected porous Ni/SiC skeleton (3D Ni/SiC) was synthesized by binder-free hydrogen bubble template-assisted electrodeposition in an electrolyte containing Ni²⁺ ions and SiC nanopowders. This 3D Ni/SiC skeleton served as a substrate for directly synthesizing nickel–cobalt layered double hydroxide (LDH) nanosheets via electrodeposition, allowing the formation of a nickel–cobalt LDH nanosheet-decorated 3D Ni/SiC skeleton (NiCo@3D Ni/SiC). The multiscale hierarchical structure of NiCo@3D Ni/SiC was attributed to the synergistic interaction between the pseudocapacitor (3D Ni skeleton and Ni–Co LDH) and electrochemical double-layer capacitor (SiC nanopowders). It provided a large specific surface area to expose numerous active Ni and Co sites for Faradaic redox reactions, resulting in an enhanced pseudocapacitance. The as-fabricated NiCo@3D Ni/SiC structure demonstrated excellent rate capability with a high areal capacitance of 1565 mF cm⁻² at a current density of 1 mA cm⁻². Additionally, symmetrical supercapacitor devices based on this structure successfully powered commercial light-emitting diodes, indicating the potential of as-fabricated NiCo@3D Ni/SiC in practical energy storage applications. Full article

In this study, nanoporous gold (NPG) was deposited on a screen-printed carbon electrode (SPCE) by the dynamic hydrogen bubble template (DHBT) method to prepare an electrochemical sensor for the simultaneous determination of Pb²⁺ and Cu²⁺ by square wave anodic stripping voltammetry (SWASV). The electrodeposition potential and electrodeposition time for NPG/SPCE preparation were investigated thoroughly. Scanning electron microscopy (SEM) and energy-dispersive X-ray diffraction (EDX) analysis confirmed successful fabrication of the NPG-modified electrode. Electrochemical characterization exhibits its superior electron transfer ability compared with bare and nanogold-modified electrodes. After a comprehensive optimization, Pb²⁺ and Cu²⁺ were simultaneously determined with linear range of 1–100 μg/L for Pb²⁺ and 10–100 μg/L for Cu²⁺, respectively. The limits of detection were determined to be 0.4 μg/L and 5.4 μg/L for Pb²⁺ and Cu²⁺, respectively. This method offers a broad linear detection range, a low detection limit, and good reliability for heavy metal determination in drinking water. These results suggest that NPG/SPCE holds great promise in environmental and food applications. Full article

Nickel–tungsten (Ni-W) alloys are gaining significant attention due to their superior hardness, wear resistance, anti-corrosion and electrochemical hydrogen evolution reaction (HER) activity. In this work, porous and crack Ni-W alloys with different W contents were prepared in a pyrophosphate bath. The key to forming a porous structure is a very high current density over 300 mA cm⁻². The HER activity of porous and crack Ni-W alloys was studied by means of electrochemical technologies of linear sweep voltammetry (LSV), Tafel curves (Taf) and electrochemical impedance spectroscopy (EIS). Compared with the crack Ni-W alloy, the porous Ni-W alloy exhibits improved alkaline electrochemical HER performances, which can deliver a current density of 10 mA cm⁻² at 166 mV (η10) vs. RHE (reversible hydrogen electrode). Full article

Copper-based electrocatalytic materials play a critical role in various electrocatalytic processes, including the electroreduction of carbon dioxide and nitrate. Three-dimensional nanostructured electrodes are particularly advantageous for electrocatalytic applications due to their large surface area, which facilitates charge transfer and mass transport. However, the real surface area (RSA) of electrocatalysts is a crucial parameter that is often overlooked in experimental studies of high-surface-area copper electrodes. In this study, we investigate the roughness factors of electrodeposited copper foams with varying thicknesses and morphologies, obtained using the hydrogen bubble dynamic template technique. Underpotential deposition (UPD) of metal adatoms is one of the most reliable methods for estimating the RSA of highly dispersed catalysts. We aim to illustrate the applicability of UPD of lead for the determination of the RSA of copper deposits with hierarchical porosity. To find the appropriate experimental conditions that allow for efficient minimization of the limitations related to the slow diffusion of lead ions in the pores of the material and background currents of the reduction of traces of oxygen, we explore the effect of lead ion concentration, stirring rate, scan rate, monolayer deposition time and solution pH on the accuracy of RSA estimates. Under the optimized measurement conditions, Pb UPD allowed to estimate roughness factors as high as 400 for 100 µm thick foams, which translates into a specific surface area of ~6 m²·g⁻¹. The proposed measurement protocol may be further applied to estimate the RSA of copper deposits with similar or higher roughness. Full article

Prostate cancer is a disease with a high incidence and mortality rate in men worldwide. Serum prostate-specific antigens (PSA) are the main circulating biomarker for this disease in clinical practices. In this work, we present a portable and reusable microfluidic device for PSA quantification. This device comprises a polymethyl methacrylate microfluidic platform coupled with electrochemical detection. The platinum working microelectrode was positioned in the outflow region of the microchannel and was modified with carbon nanofibers (CNF)-decorated gold nanoporous (GNP) structures by the dynamic hydrogen bubble template method, through the simultaneous electrodeposition of metal precursors in the presence of CNF. CNF/GNP structures exhibit attractive properties, such as a large surface to volume ratio, which increases the antibody’s immobilization capacity and the electroactive area. CNFs/GNP structures were characterized by scanning electron microscopy, energy dispersive spectrometry, and cyclic voltammetry. Anti-PSA antibodies and HRP were employed for the immune-electrochemical reaction. The detection limit for the device was 5 pg mL⁻¹, with a linear range from 0.01 to 50 ng mL⁻¹. The coefficients of variation within and between assays were lower than 4.40%, and 6.15%, respectively. Additionally, its clinical performance was tested in serum from 30 prostate cancer patients. This novel device was a sensitive, selective, portable, and reusable tool for the serological diagnosis and monitoring of prostate cancer. Full article

Nanostructuring of metals is nowadays considered as a promising strategy towards the development of materials with enhanced electrochemical performance. Porous and fully dense CuNi films were electrodeposited on a Cu plate by electrodeposition in view of their application as electrocatalytic materials for the hydrogen evolution reaction (HER). Porous CuNi film were synthesized using the hydrogen bubble template electrodeposition method in an acidic electrolyte, while fully dense CuNi were electrodeposited from a citrate-sulphate bath with the addition of saccharine as a grain refiner. The prepared films were characterized chemically and morphologically by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The Rietveld analysis of the XRD data illustrates that both CuNi films have a nanosized crystallite size. Contact angle measurements reveal that the porous CuNi film exhibits remarkable superhydrophobic behavior, and fully dense CuNi film shows hydrophilicity. This is predominately ascribed to the surface roughness of the two films. The HER activity of the two prepared CuNi films were investigated in 1 M KOH solution at room temperature by polarization measurements and electrochemical impedance spectroscopy (EIS) technique. Porous CuNi exhibits an enhanced catalysis for HER with respect to fully dense CuNi. The HER kinetics for porous film is processed by the Volmer–Heyrovsky reaction, whereas the fully dense counterpart is Volmer-limited. This study presents a clear comparison of HER behavior between porous and fully dense CuNi films. Full article

Fe and Pd thin film samples have been fabricated in a rapid fashion utilizing the versatile technique of dynamic hydrogen bubble template (DHBT) method via potentiostatic electrodeposition over a copper substrate. The morphology of the samples is dendritic, with the composition being directly proportional to the deposition time. All the samples have been tested as SERS substrates for the detection of Rhodamine 6G (R6G) dye. The samples perform very well, with the best performance shown by the Pd samples. The lowest detectable R6G concentration was found to be 10⁻⁶ M (479 μgL⁻¹) by one of the Pd samples with the deposition time of 180 s. The highest enhancement of signals noticed in this sample can be attributed to its morphology, which is more nanostructured compared to other samples, which is extremely conducive to the phenomenon of localized surface plasmon resonance (LSPR). Overall, these samples are cheaper, easy to prepare with a rapid fabrication method, and show appreciable SERS performance. Full article

A relatively static and unique bubble template is successfully realized on a microporous substrate by controlling the surface tensions of the electrodeposit solution, and a nickel layer containing macropores is prepared using this bubble template. When the surface tension of the solution is 50.2 mN/m, the desired bubble template can be formed, there are fewer bubbles attached to other areas on the substrate, and a good nickel layer is obtained. In the analysis of the macropore formation process, it is found that the size of the bell-mouthed macropores can be tailored by changing the solution stirring speed or the current density to adjust the growth rate of the bubble template. The size change of a macropore is measured by the profile angle of the longitudinal macropore, section. As the solution stirring speed increases from 160 to 480 r/min, the angle range of the bell-mouthed macropores cross-sectional profile is increased from 21.0° to 44.3°. In addition, the angle range of the bell-mouthed macropore cross-sectional profile is increased from 39.3° to 46.3° with the current density increasing from 1 to 2.5 A/dm². Different from the dynamic hydrogen bubble template, the bubble template implemented in this paper stays attached on the deposition and grows slowly, which is novel and interesting, and the nickel layer containing macropores prepared using this bubble template is applied in completely different fields. Full article

The structure of Ni films is essential to their electrocatalytic performance for hydrogen evolution reaction (HER). The pH value and EDTA (ethylene diamine tetraacetic acid) additive are important factors for the structure control of electrodeposited metal films due to their adjustment of metal electrocrystallization and hydrogen evolution side reactions. The structures of Ni films from 3D (three-dimensional) porous to compact and flat structure are electrodeposited by adjusting solution pH values or adding EDTA. It is found that when pH value increases from 7.7 to 8.1, 3D porous films change to compact films with many protrusions. Further increasing the pH value or adding 0.1 M EDTA causes compact and flat films without protrusions to appear. When pH ≤ 7.7, hydrogen bubbles with large break-off diameter are easily adsorbed on film surface acting as porous structure templates, and the electroactive ion species, Ni²⁺ and Ni(NH₃)_n²⁺ complexes with low coordination number (n ≤ 3), possess high reduction overpotential, which is beneficial to forming protrusions and smaller particles. So, porous Ni films are electrodeposited. In solutions with pH ≥ 8.1 or 0.1 M EDTA, Ni(NH₃)_n²⁺ complexes with high coordination number (6 ≥ n ≥ 3) and hexadentate chelate are formed. Due to the improved wettability, bubbles with a small break-off diameter rapidly detach the film surface resulting in strong stirring. The reduction overpotential is reduced, leading to the formation of larger particles. Therefore, the solution leveling ability increases, and it is difficult to form protrusions, thus it forms a compact and flat film. The 3D porous film exhibits excellent catalytic performance for HER due to the large catalytic activity area. Full article

Water scarcity is a worldwide issue that significantly affects the environment, population, and economy of the arid zones. In this study, we report a straightforward method for water-harvesting based on modifications of the surface wettability. Using magnesium chloride, lauric acid, and electrodeposition process, a superhydrophobic surface (155°) is obtained. Morphological characterization techniques allow determination of the characteristic flower-like microstructures combined with close packed nanoarrays that lead to the hierarchical structure. Furthermore, the coating presents vertically aligned microarrays in a non-linear cone morphology formed by dynamic templating of hydrogen bubbles. From a chemical point of view, magnesium laurate is responsible for the surface tension decrease. To determine the durability of the obtained surface ultra-violet (UV) light test and abrasive paper test, tests are carried out revealing high durability against these severe conditions. The water-harvesting ability of the superhydrophobic surface is studied at 45° and 90° tilted samples. The capacity of the water to be harvested efficiently is found to be at 90° tilt under fog conditions. The use of green reactants associated with this hierarchical structure broadens a new scope for sustainable freshwater collection and it becomes an excellent example of a green solution. Full article

In this paper, we present the first highly porous gold (h-PG) microneedles-based second-generation biosensor for minimally invasive monitoring of glucose in artificial interstitial fluid (ISF). A highly porous microneedles-based electrode was prepared by a simple electrochemical self-templating method that involves two steps, gold electrodeposition and hydrogen bubbling at the electrode, which were realized by applying a potential of −2 V versus a saturated calomel electrode (SCE). The highly porous gold surface of the microneedles was modified by immobilization of 6-(ferrocenyl)hexanethiol (FcSH) as a redox mediator and subsequently by immobilization of a flavin adenine dinucleotide glucose dehydrogenase (FAD-GDH) enzyme using a drop-casting method. The microneedles-based FcSH/FAD-GDH biosensor allows for the detection of glucose in artificial interstitial fluid with an extended linear range (0.1–10 mM), high sensitivity (50.86 µA cm⁻² mM⁻¹), stability (20% signal loss after 30 days), selectivity (only ascorbic acid showed a response about 10% of glucose signal), and a short response time (3 s). These properties were favourably compared to other microneedles-based glucose biosensors reported in the literature. Finally, the microneedle-arrays-based second-generation biosensor for glucose detection was tested in artificial interstitial fluid opportunely spiked with different concentrations of glucose (simulating healthy physiological conditions while fasting and after lunch) and by placing the electrode into a simulated chitosan/agarose hydrogel skin model embedded in the artificial ISF (continuous glucose monitoring). The obtained current signals had a lag-time of about 2 min compared to the experiments in solution, but they fit perfectly into the linearity range of the biosensor (0.1–10 mM). These promising results show that the proposed h-PG microneedles-based sensor could be used as a wearable, disposable, user-friendly, and automated diagnostic tool for diabetes patients. Full article

Metal foams offer a substantial specific surface area and sturdy frame, which makes them great candidates for various applications such as catalysts, sensors, heat sinks, etc. Cobalt and its various compounds are being considered as a cheaper alternative for precious and rare metal catalysts. The cobalt foams have been electrodeposited under galvanostatic and current pulse modes; the porous surface was created using a dynamic hydrogen bubble template. In order to obtain the highest porosity, four different solutions were tested, as well as a wide current density window (0.6–2.5 A/cm²), in addition many different combinations of pulse durations were applied. The effects of surfactant (isopropanol) on porosity were also investigated. The morphology of obtained foams was examined by SEM coupled with EDS, and XRD spectroscopy. True surface area was estimated based on the values of a double electric layer capacitance that was extracted from EIS data. Cobalt foams were modified using K₃[Fe(CN)₆] solution and cyclic voltammetry to form a cobalt hexacyanoferrate complex on the foam surface. In order to find optimal modification conditions, various potential scan rates and numbers of cycles were tested as well. Free chlorine sensing capabilities were evaluated using chronoamperometry. Full article

Glucose concentration is an important physiological index, therefore methods for sensitive detection of glucose are important. In this study, Au foam was prepared by electrodeposition with a dynamic gas template on an Au nanoparticle/Si substrate. The Au foam showed ultrasensitivity, high selectivity, and long-term stability in the quantitative detection of glucose. The foam was used as an electrode, and the amperometric response indicated excellent catalytic activity in glucose oxidation, with a linear response across the concentration range 0.5 μM to 12 mM, and a limit of detection of 0.14 μM. High selectivity for interfering molecules at six times the normal level and long-term stability for 30 days were obtained. The results for electrochemical detection with Au foam of glucose in human serum were consistent with those obtained with a sensor based on surface-enhanced Raman spectroscopy and a commercial sensor. This proves that this method can be used with real samples. These results show that Au foam has great potential for use as a non-enzymatic glucose sensor. Full article