ABSTRACT
Keeping global warming at 2 degrees and below as stated in the "Paris Climate Agreement" and minimizing emissions can only be achieved by establishing a hydrogen (H2) ecosystem. Therefore, H2 technologies stand out in terms of accomplishing zero net emissions. Although H2 is the most abundant element in the known universe, molecular H2 is very rare in nature and must be produced. In H2 production, reforming natural gas and renewable hydrogen processes using electrolyzers comes to the fore. The key to all these technologies is to enhance production speed, performance, and system lifetime. At this point, composite membranes used in both processes come to the fore. This review article summarizes composite membrane technologies used in methane, ethanol, and biomass steam reforming processes, proton exchange membranes, alkaline water electrolysis, and hybrid sulfur cycle. In addition to these common H2 production technologies at large quantities, the innovative systems developed with solar energy integration for H2 generation were linked to composite membrane utilization. This study aimed to draw attention to the importance of composite membranes in H2 production. It aims to prepare a guiding summary for those working on membranes by combining the latest and cutting-edge studies on this subject.
ABSTRACT
Recent advances in nanoparticle materials can facilitate the electro-reduction of carbon dioxide (CO2) to form valuable products with high selectivity. Copper (Cu)-based electrodes are promising candidates to drive efficient and selective CO2 reduction. However, the application of Cu-based chalcopyrite semiconductors in the electrocatalytic reduction of CO2 is still limited. This study demonstrated that novel zinc oxide (ZnO)/copper indium gallium sulfide (CIGS)/indium sulfide (InS) heterojunction electrodes could be used in effective CO2 reduction for formic acid production. It has been determined that Faradaic efficiencies for formic acid production using ZnO nanowire (NW) and nanoflower (NF) structures vary due to structural and morphological differences. A ZnO NW/CIGS/InS heterojunction electrode resulted in the highest efficiency of 77.2% and 0.35 mA cm-2 of current density at a -0.24 V (vs. reversible hydrogen electrode) bias potential. Adding a ZTO intermediate layer by the spray pyrolysis method decreased the yield of formic acid and increased the yield of H2. Our work offers a new heterojunction electrode for efficient formic acid production via cost-effective and scalable CO2 reduction.
ABSTRACT
Highly stable platinum (Pt) and ruthenium (Ru)-based catalysts on titanium oxide (TiO2) nanoparticle support were prepared. The productivity of hydrogen generation from sodium borohydride (NaBH4) hydrolysis was observed to be as high as 95%. The activation energies for the hydrolysis reaction in the presence of Ru/TiO2 in aqueous and alkaline solutions were 62.00 and 64.65 kJ mol-1, respectively. On the other hand, the activation energy value of the hydrolysis reaction with the Pt/TiO2 catalyst decreased from 60.5 to 53.2 kJ mol-1, and the solution was changed from an aqueous to an alkaline medium. The experimental results have indicated that NaOH concentration (ranging from 0.5 to 2 M) affected the hydrogen generation rate (HGR) differently for both metals on the TiO2 support. Consequently, the HGR of the hydrolysis reaction in the presence of the Ru/TiO2 catalyst decreased with increasing NaOH concentration, whereas the Pt/TiO2 catalyst efficiency increased with increasing NaOH concentration.
ABSTRACT
In this study, zinc oxide (ZnO) powders in two different morphologies, nanowire (NW) and nanoflower (NF), have been synthesized by the hydrothermal method. The eligibility of the pristine ZnO nanopowders as a photo-active material has been revealed by designing P-SC devices via the facile drop-casting method on both glass and plastic substrates in large-area applications. The impact of physical properties and especially defect structures on photo-supercapacitor (P-SC) performance have been explored. Although the dark Coulombic efficiency (CE%) of both NW and NF-based P-SC were very close to each other, the CE% of NW P-SC increased 3 times, while the CE% of NF P-SC increased 1.7 times under the UV-light. This is because the charge carriers produced under light excitation, extend the discharge time, and as confirmed by electron paramagnetic resonance, photoluminescence, and transmission electron microscopy analyses, the performance of P-SCs made from NF powders was relatively low compared to those produced from NW due to the high core defects in NF powders. The energy density of 78.1 mWh kg-1 obtained for NF-based P-SCs is very promising, and the capacitance retention value of almost 100% for 3000 cycles showed that the P-SCs produced from these materials were entirely stable. Compared to the literature, the P-SCs we propose in this study are essential for new generation energy storage systems, thanks to their ease of design, adaptability to mass production for large-area applications, and their ability to store more energy under illumination.
ABSTRACT
The malfunctioning in the release of acetylcholine (ACh+), leading to consequential damages in the neural system, has become an impulsion for the development of numerous progressive transport and detection gadgets. However, several challenges, such as laterality and complexity of transport devices, low precision of amperometric detection systems, and sumptuous, multistaged enzymatic quantification methods, have not yet been overcome. Herein, ionomers, because of their selective ion transporting nature, are chosen as suitable candidates for being implemented into both targeted ACh+ delivery and sensing systems. Based on these two approaches, for the very first time in the literature, the disulfonated poly(arylene ether sulfone) membrane is concurrently (i) used in the mimicry of transduction of the electrical-to-ionic signal in a neural network as "Acetylcholine Pen" (ACh+ Pen) and (ii) operated as a highly sensitive, conductivity-based ACh+ quantifier. Our dual device, being able to operate under an actual action potential of 55 mVbias, shows a strong potential of future applicability in real-time ionic delivery-and-sensing systems.
Subject(s)
Acetylcholine/analysis , Polymers/chemistry , Particle Size , Surface PropertiesABSTRACT
In this report, the growth of zinc oxide (ZnO) nanocrystals with various morphologies, nanoflower, nanosheet, and nanorod, on flexible stainless steel (SS) foils to be utilized as photoanodes in photoelectrochemical (PEC) solar cells has been presented. It has been aimed to provide flexibility and adaptability for the next generation systems with the incorporation of SS foils as electrode into PEC cells. Therefore, physical deformation tests have been applied to the prepared ZnO thin film photoanodes. These thin films have been thoroughly characterized before and after straining for better understanding the relationship between the morphology, straining effect and photoelectrochemical efficiency. We observed a notable increase in the maximum incident photon-to-current efficiency (IPCE) and durability of all ZnO photoelectrodes after straining process. The increase in IPCE values by 1.5 and 2.5 folds at 370 nm has been observed for nanoflower and nanorod morphologies, respectively after being strained. The maximum IPCE of 69% has been calculated for the ZnO nanorod structures after straining. Bending of the SS electrodes resulted in the more oriented nanorod arrays compared to its flat counterpart, which improved both the light absorption and also the photo-conversion efficiency drastically. The finite-difference time-domain simulations have also been carried out to examine the optical properties of flat and bent ZnO electrodes. Finally, it has been concluded that SS photoanodes bearing ZnO semiconducting material with nanoflower and nanorod morphologies are very promising candidates for the solar hydrogen generator systems in terms of efficiency, durability, flexibility, and lightness in weight.
