Ultra-Efficient and Cost-Effective Platinum Nanomembrane Electrocatalyst for Sustainable Hydrogen Production

Hydrogen production through hydrogen evolution reaction (HER) offers a promising solution to combat climate change by replacing fossil fuels with clean energy sources. However, the widespread adoption of efficient electrocatalysts, such as platinum (Pt), has been hindered by their high cost. In this study, we developed an easy-to-implement method to create ultrathin Pt nanomembranes, which catalyze HER at a cost significantly lower than commercial Pt/C and comparable to non-noble metal electrocatalysts. These Pt nanomembranes consist of highly distorted Pt nanocrystals and exhibit a heterogeneous elastic strain field, a characteristic rarely seen in conventional crystals. This unique feature results in significantly higher electrocatalytic efficiency than various forms of Pt electrocatalysts, including Pt/C, Pt foils, and numerous Pt single-atom or single-cluster catalysts. Our research offers a promising approach to develop highly efficient and cost-effective low-dimensional electrocatalysts for sustainable hydrogen production, potentially addressing the challenges posed by the climate crisis.

Lattice distortion-driven band gap engineering and enhanced electrocatalytic activity of Mn-substituted nanostructured SrTiO3 materials: A comprehensive investigation

The lattice distortion and electrocatalytic activity are investigated by the mono-substituent of Mn with different concentrations to generate localized states in the electronic structure of SrTiO3. The sol-gel approach has been employed to fabricate SrTiO3 and SrTi1-xMnxO3 nanostructures (NSs). The structural analysis indicates Mn incorporation into Ti sites of SrTiO3, which shifts the lattice towards a higher diffraction angle with a single-phase cubic structure. The optical absorption spectra exhibit a decrease in band gap from 3.27 to 1.89 eV and reveal the shift in band edge positions towards the visible region. XPS analysis is carried out to confirm the formation of oxygen vacancies and valence band edge position. For SrTi0.88Mn0.12O3, OER and HER have the overpotential of 445 and 157 mV at a current density of 100 and 10 mA cm-2. Hence, the substitution of Mn (x = 0.12) into SrTiO3 lattice results in lattice distortion that enhances the electrochemical performance compared to SrTiO3. The current work manifestly established the optimal Mn composition (x = 0.12) in SrTiO3 lattice as desirable materials with defective valence states for required electrocatalytic redox potential as well as the acceleration of charge transfer kinetics towards water splitting applications.

Physicochemical Properties of High-Entropy Oxides

The development of industry has triggered an increasingly severe demand for new functional materials. In recent years, researches on high-entropy oxides (HEOs) are more comprehensive and in-depth, and their fascinating properties are gradually known to the public. The unique elemental synergistic effect and lattice distortion endow the high-entropy family with various untapped potential, and wide application fields and outstanding performance of HEOs make them candidates for future materials. In this review, the concept, structure, and synthesis of HEOs are firstly highlighted. Secondly, a variety of excellent properties and applications in the fields of mechanics, electrics, thermotics, optics and magnetics are summarized. This work provides a comprehensive overview about HEOs, facilitating the development of modern functionalities of the high-entropy family.

Cordierite and citric acid regulate crystal structure of manganese oxide for effective selective catalytic reduction of nitrogen oxide

Catalyst is the key to effective selective catalytic reduction of nitrogen oxide, and developing catalyst is always one of the hottest topics in both field of industry and academy. In order to realize an industrial application, one catalyst must grow on a specific support. However, seldom work compared the difference of catalyst growth with or without support. In this work, Mn²⁺ growth on cordierite (a typical commercial catalyst support) was investigated. The formed active species were detailedly characterized. As a result, orthorhombic cordierite guided Mn²⁺ to form orthorhombic oxide (γ-MnO₂). In comparison, Mn²⁺ preferred to form tetragonal β-MnO₂ without the guide of cordierite. During the synthesis, cordierite and citric acid promoted γ-MnO₂ dispersion, increased growth of exposed (301) facet, and created lattice distortion between (301) and (101) planes. β-MnO₂ mainly exposed (101) facet. The best catalyst was γ-MnO₂, which was mostly dominated by (301) facet and had an obvious lattice distortion from 75° to 78° between (301) and (101) planes. In comparison, 0.1 g of the γ-MnO₂ reached a catalytic conversion rate 1.6 times bigger than 1.0 g of β-MnO₂ at 250 °C. This work helps to understand guiding effect of support on formed catalytic species, which is in favor of developing effective commercial catalysts for environmental pollutants.

On the Paramagnetic-Like Susceptibility Peaks at Zero Magnetic Field in [Formula: see text] Single Crystals

A weakly temperature-dependent paramagnetic-like susceptibility peak at zero magnetic field is observed in [Formula: see text] with only marginal amount of ferromagnetic impurities. The ferromagnetic hysteresis loop and the magnetic moment splitting between zero-field-cooled and field-cooled processes indicate ferromagnetism in the samples. The paramagnetic-like susceptibility peak height is proportional to the remanent magnetic moment of hysteresis loops. High-resolution transmission electron microscope image supports that the observed ferromagnetic feature originates from lattice distortion. These results imply that the weakly temperature-dependent paramagnetic-like susceptibility peak originates from weak lattice distortion and/or superparamagnetism.

The Lattice Distortion-Induced Ferromagnetism in the Chemical-Bonded MoSe2/WSe2 at Room Temperature

Ferromagnetism to non-ferromagnetism transition is detected in a chemically bonded MoSe[Formula: see text]/WSe[Formula: see text] powder with different thermal annealing temperatures. All samples exhibit ferromagnetism and Raman redshift, except for the 1100 °C thermally annealed sample in which the MoSe[Formula: see text] and WSe[Formula: see text] are thermally dissociated and geometrically separated. The element analysis reveals no significant element ratio difference and detectable magnetic elements in all samples. These results support that, in contrast to the widely reported structure defect or transition element dopant, the observed ferromagnetism originates from the structure distortion due to the chemical bonding at the interface between MoSe[Formula: see text] and WSe[Formula: see text].

Ru-incorporated Co3O4 nanoparticles from self-sacrificial ZIF-67 template as efficient bifunctional electrocatalysts for rechargeable metal-air battery

Ru-incorporated Co₃O₄ nanoparticles have been synthesized from self-sacrificial ZIF-67 template and utilized as efficient electrocatalysts towards oxygen reduction and evolution reactions (ORR and OER). Amongst, Ru@Co₃O₄-1.0 exhibited the optimum electrocatalytic behavior with an ultra-low potential gap (0.84 V) between the OER potential (1.61 V at 10 mA cm^-2) and ORR half-wave potential (0.77 V). The zinc-air battery using Ru@Co₃O₄-1.0 as a cathode presented high specific capacity (788.1 mAh g^-1) and power density (101.2 mW cm^-2). Meanwhile, this battery possessed relatively lower voltage gap and higher cycling stability compared with the commercial Pt/C-based one. Ruthenium incorporation induced remarkable lattice expansion of Co₃O₄ and engineered more oxygen vacancies, promoting the lattice oxygen mobility from the subsurface/bulk phase onto surface. All these properties were recognized to be the crucial parameters for electrocatalytic activity improvement. This work provided a facile approach to design highly active metal oxide with broad potentiality for rechargeable metal-air batteries.

Unveiling the photoluminescence regulation of colloidal perovskite quantum dots via defect passivation and lattice distortion by potassium cations doping: Not the more the better

In this work, we have first demonstrated that the potassium cation doping effect on photoluminescence (PL) regulation of CH₃NH₃PbBr₃ (CH₃NH₃⁺=MA⁺) colloidal perovskite quantum dots (QDs) is significantly different from the other alkali cation doping effects. The PL intensity will be generally enhanced with the increase doping amounts of other alkali cations. Herein, we have unveiled that the PL of the potassium-doped perovskite QDs is initially prompted by the potassium ions doping and then inhibited with further growing doping amount of the potassium ions. Furthermore, we have also demonstrated that the PL inhibition phenomenon is ascribed as quick trapping of redundant photogenerated electrons by the trap states after huge amount doping besides defect passivation and octahedral structure distortion induced by the initial doping. At the same time, the specific excited state transient absorption and the lifetime of MA_xK_1-xPbBr₃ also confirm that the radiation recombination process is enhanced via defect passivation and lattice distortion, which is induced by moderate potassium cations doping. In addition, the PL of colloidal perovskite quantum dots can be adjusted from orange to cyan within the wavelength range of 300 nm - 600 nm and exhibit better stability.

Hydrothermal-aging-induced lattice distortion in yttria-stabilized zirconia using EBSD technique

The destabilization problem is of importance in the application of yttria-stabilized zirconia (YSZ) bio-ceramic in the oral environment due to phase transformation between tetragonal to monoclinic. Thus, in this study, the lattice distortion induced by hydrothermal aging in yttria-stabilized zirconia (YSZ) was investigated, in which YSZ specimens were subjected to hydrothermal-aging treatment for 0-48 h. The Kikuchi-band based method was employed to calculate the lattice distortion after phase transformation and the results from EBSD were compared with these obtained by X-ray diffraction (XRD). Both measurement methods showed a similar tendency of the lattice change in the a- and c- axes. EBSD results showed that the strain rates were 7.98 % and -5.03 % at the a- and c-axes, respectively. A significant decrease in the c/a ratio from 1.429 to 1.257 for the tetragonal matrix after 48 h aging is observed, which indicated Kikuchi-band based method using EBSD technique can successfully determine the local strain in tetragonal matrices.

Local Lattice Distortion Activate Metastable Metal Sulfide as Catalyst with Stable Full Discharge-Charge Capability for Li-O2 Batteries

The direct lattice strain, either distortion, compressive, or tensile, can efficiently alter the intrinsic electrocatalytic property of the catalysts. In this work, we report a novel and effective strategy to distort the lattice structure by constructing a metastable MoSSe solid solution and thus, tune its catalytic activity for the Li-O₂ batteries. The lattice distortion structure with inequivalent interplanar spacing between the same crystals plane were directly observed in individual MoSSe nanosheets with transmission electron microscopy and aberration-corrected transmission electron microscopy. In addition, in situ transmission electron microscopy analysis revealed the fast Li⁺ diffusion across the whole metastable structure. As expected, when evaluated as oxygen electrode for deep-cycle Li-O₂ batteries, the metastable MoSSe solid solution deliver a high specific capacity of ∼730 mA h g^-1 with stable discharge-charge overpotentials (0.17/0.49 V) over 30 cycles.