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Exploring the influencing factors of the electrochemical reduction process on the PEC water splitting performance of rutile TiO.sub.2
The self-doping of oxygen vacancy and Ti.sup.3+ by electrochemical reduction (ER) method has been proved to be an effective means to improve the PEC performance of TiO.sub.2. However, the effect of the surface structure on ER treatment remains ambiguous. In this work, three kinds of nanostructured rutile TiO.sub.2 (nanowire arrays (TNWs), etched nanowire arrays (E-TNWs) and nanorod arrays (TNRs)) were reduced electrochemically to explore the factors influencing the ER process of rutile TiO.sub.2. The experimental results show that alkaline environment (1 M NaOH) is more conducive to the occurrence of ER reaction. And the reduced three kinds of nanostructured TiO.sub.2 photoanodes show a significantly higher photocurrent density of about 1.46, 1.65 and 1.45 mA cm.sup.-2 at 1.23 V vs. relative hydrogen electrode (RHE), respectively, which are 15, 16 and 1.1 times that of pristine TiO.sub.2. The different degrees of photocurrent density enhancement can be ascribed to the different degrees of electrochemical reduction of TiO.sub.2 with different crystallinity and exposed crystal facets as well as specific surface area. This study provides new insights into the mechanism of electrochemical reduction method.
Journal Article
Hydrogen
\"Hydrogen is the most widespread element and one of the building blocks of life. First appearing when the Big Bang created the universe, hydrogen is now part of human technologies that could change the future. People have used liquid hydrogen to send astronauts into space and hydrogen gas to drive families to the store. In this informative text, we'll explore the first element in the periodic table, looking at its properties and finding its hiding places. From our bodies to the Sun, hydrogen is everywhere!\"-- Provided by publisher.
Book
Does Metal Matter: Comparing Photophysical Properties of Bis-Cyclometalated Alkynylphosphonium Au Complexes
In this work, two series of Au(III) and Pt(II) alkynylphosphonium complexes of composition [M(CNC)(C[sub.2]−L−P(CH[sub.3])Ph[sub.2])][sup.n+] Pt1–Pt3 (n = 0) and Au1–Au3 (n = 1), (CNC = 2,6-diphenylpyridine; L = phenyl, biphenyl, naphthyl) were synthesized and characterized to discover the similarities and differences in photophysical properties between isoelectronic metallocentres. It is shown that Au(III) and Pt(II) complexes obtained demonstrate different photophysical properties despite isoelectronic metal centres, and some reasons for that are discussed based on experimental data and quantum-chemical calculation results. Complex Pt1 also demonstrated the first example of room-temperature solution phosphorescence in the family of [Pt(CNC)(alkynyl)] complexes. It has been found that the crystal packing of Pt1 contains a Pt–H interaction, qualified by quantum-chemical calculations as a unique hydrogen bond.
Journal Article
Low-temperature fabrication of morphology-controllable Cu.sub.2O for electrochemical CO.sub.2 reduction
Cu.sub.2O has been successfully synthesized in different morphologies/sizes (nanoparticles and octahedrons) via a low-temperature chemical reduction method. Trapping metal ions in an ice cube and letting them slowly melt in a reducing agent solution is the simplest way to control the nanostructure. Enhancement of charge transfer and transportation of ions by Cu.sub.2O nanoparticles was shown by cyclic voltammetry and electrochemical impedance spectroscopy measurements. In addition, nanoparticles exhibited higher current densities, the lowest onset potential, and the Tafel slope than others. The Cu.sub.2O electrocatalyst (nanoparticles) demonstrated the Faraday efficiencies (FEs) of CO, CH.sub.4, and C.sub.2H.sub.6 up to 11.90, 76.61, and 1.87%, respectively, at -0.30 V versus reference hydrogen electrode, which was relatively higher FEs than other morphologies/sizes. It is mainly attributed to nano-sized, more active sites and oxygen vacancy. In addition, it demonstrated stability over 11 h without any decay of current density. The mechanism related to morphology tuning and electrochemical CO.sub.2 reduction reaction was explained. This work provides a possible way to fabricate the different morphologies/sizes of Cu.sub.2O at low-temperature chemical reduction methods for obtaining the CO, CH.sub.4, and C.sub.2H.sub.6 products from CO.sub.2
Journal Article
Sensors for safety and process control in hydrogen technologies
The use of hydrogen generated from renewable energy sources is expected to become an essential component of a low-carbon, environmentally friendly energy supply, spurring the worldwide development of hydrogen technologies. This title provides practical, expert-driven information on modern sensors for hydrogen and other gases as well as physical parameters essential for safety and process control in hydrogen technologies. It illustrates how sensing technologies can ensure the safe and efficient implementation of the emerging global hydrogen market.
Book
Enhanced Electrocatalytic Performance of P-Doped MoSsub.2/rGO Composites for Hydrogen Evolution Reactions
This study is based on the strategies of composite and element doping. Herein, P-MoS[sub.2]/rGO materials were synthesized using a solvent-assisted hydrothermal method. The MoS[sub.2] nanosheets were uniformly and vertically grown on rGO; meanwhile, the optimized structure of MoS[sub.2] was achieved by P doping, resulting in improved catalytic performance and structural stability. Under alkaline conditions, the P-MoS[sub.2]/rGO catalyst exhibits good electrocatalytic activity, demonstrating a Tafel slope of 70.7 mV dec[sup.−1] and an overpotential of 172.8 mV at 10 mA/cm[sup.2]. Notably, even after 3000 consecutive LSV tests, the curves still show a high degree of overlap, indicating exceptional stability.
Journal Article
Recent Progress of Ion-Modified TiOsub.2 for Enhanced Photocatalytic Hydrogen Production
Harnessing solar energy to produce hydrogen through semiconductor-mediated photocatalytic water splitting is a promising avenue to address the challenges of energy scarcity and environmental degradation. Ever since Fujishima and Honda’s groundbreaking work in photocatalytic water splitting, titanium dioxide (TiO[sub.2]) has garnered significant interest as a semiconductor photocatalyst, prized for its non-toxicity, affordability, superior photocatalytic activity, and robust chemical stability. Nonetheless, the efficacy of solar energy conversion is hampered by TiO[sub.2]’s wide bandgap and the swift recombination of photogenerated carriers. In pursuit of enhancing TiO[sub.2]’s photocatalytic prowess, a panoply of modification techniques has been explored over recent years. This work provides an extensive review of the strategies employed to augment TiO[sub.2]’s performance in photocatalytic hydrogen production, with a special emphasis on foreign dopant incorporation. Firstly, we delve into metal doping as a key tactic to boost TiO[sub.2]’s capacity for efficient hydrogen generation via water splitting. We elaborate on the premise that metal doping introduces discrete energy states within TiO[sub.2]’s bandgap, thereby elevating its visible light photocatalytic activity. Following that, we evaluate the role of metal nanoparticles in modifying TiO[sub.2], hailed as one of the most effective strategies. Metal nanoparticles, serving as both photosensitizers and co-catalysts, display a pronounced affinity for visible light absorption and enhance the segregation and conveyance of photogenerated charge carriers, leading to remarkable photocatalytic outcomes. Furthermore, we consolidate perspectives on the nonmetal doping of TiO[sub.2], which tailors the material to harness visible light more efficiently and bolsters the separation and transfer of photogenerated carriers. The incorporation of various anions is summarized for their potential to propel TiO[sub.2]’s photocatalytic capabilities. This review aspires to compile contemporary insights on ion-doped TiO[sub.2], propelling the efficacy of photocatalytic hydrogen evolution and anticipating forthcoming advancements. Our work aims to furnish an informative scaffold for crafting advanced TiO[sub.2]-based photocatalysts tailored for water-splitting applications.
Journal Article