Nasser M. Hamdan

Developing efficient electrocatalysts for seawater splitting that operate at high current densities with long-term durability remains a significant challenge for sustainable green hydrogen generation. In this study, we report a simple one-pot hydrothermal synthesis of multi-metal phthalocyanine (Pc) catalysts incorporating Fe, Co, Ni, and Cu (FeCoNiCu-Pc) directly grown on nickel foam, which serves as a bifunctional electrocatalyst for solar-driven seawater splitting. The integration of multiple transition metals within the Pc macrocycle induces synergistic electronic interactions and optimized charge distribution, thereby facilitating enhanced electrocatalytic activity. Among the synthesized catalysts, FeCoNiCu-Pc demonstrates nearly two-fold higher activity for both the oxygen evolution (OER) and hydrogen evolution reactions (HER) compared with the single-metal-Pc counterparts. It requires minimum overpotentials of 315, 322, and 380 mV for the OER and 239, 308, and 318 mV for the HER in alkaline KOH, alkaline simulated seawater, and alkaline real seawater, respectively, at a current density of 100 mA cm−2. Furthermore, FeCoNiCu-Pc demonstrates remarkable durability, maintaining a maximum of its initial activity over 50 h at a current density of 100 mA cm−2 while maintaining its rod-like morphology. An electrolyzer fabricated using FeCoNiCu-Pc as both the anode and cathode reached 100 mA cm−2 at 1.69 V in alkaline real seawater electrolytes. As a proof of concept, the fabricated cell also exhibits stable performance under solar-driven conditions.

We present a temperature-dependent phonon behavior in NiS1.4Se0.6, a strongly correlated transition metal chalcogenide known for exhibiting a metal-insulator transition (MIT). Measurements were conducted in the temperature range of 300 K to 100 K to investigate the evolution of the Raman-active Ag phonon modes associated with Se–Se, S–Se, and S–S vibrations. Our analysis reveals a distinct change in the integrated intensity of these Ag peaks, which coincides with the MIT temperature TMI of the NiS1.4Se0.6 at 150 K. Notably, at 250 K, an additional peak appears in the integrated intensity of the phonon modes coincide with the deviation from Curie-Weiss (C-W) behavior, and the activation energy of small polarons shifts. We discuss the mechanism behind these thermally activated changes.

Indoor air quality (IAQ) is a growing public health concern, especially in environments where individuals spend the majority of their time, such as homes, educational institutions, and office environments. This study investigates the elemental composition, chemical speciation, source apportionment, and health risks associated with indoor PM _2.5 in a university building in the United Arab Emirates over a 1‐year period. An indoor sampling campaign was conducted following international standards, and elemental analysis was performed using energy‐dispersive X‐ray fluorescence (EDXRF) spectroscopy. Crystallographic phases and compound identification were performed using X‐ray diffraction (XRD) and scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM/EDS), respectively. Positive Matrix Factorization (PMF v5.0) was applied to apportion pollution sources, while health risk assessments were conducted for trace element exposure based on methods from the US EPA and the Agency for Toxic Substances and Disease Registry (ATSDR). Key indoor PM _2.5 contributors included mineral and resuspended dust, sea salt, and anthropogenic sources such as heavy oil combustion, traffic, and secondary aerosols. The health risk assessment showed that all analyzed elements (Cr, Mn, Al, As, Cu, Ni, Pb, Zn, and Mg) had hazard quotient values below 1, indicating no noncarcinogenic risk, and the carcinogenic risk values for As, Cr, Ni, and Pb were below the ATSDR’s threshold value of 1 × 10 ⁻⁶ . Multiple‐Path Particle Dosimetry modeling showed that approximately 75% of inhaled PM _2.5 deposits in the respiratory system, with younger individuals (18 years old) exhibiting slightly lower deposition. After 5 days of exposure, alveolar retention reached 0.072 mg in 21‐year‐olds and 0.066 mg in 18‐year‐olds, indicating potential for prolonged internal deposition. The findings underscore the importance of continuous monitoring and mitigation strategies to improve IAQ in densely occupied indoor environments.

CaRuO3 is a prototypical perovskite oxide among the Ruddlesden–Popper series with multi-exotic physical properties on the verge of quantum criticality. Unlike the case of the well-known ferromagnetic SrRuO3, the literature on the physical properties of the CaRuO3 system is scarce with no consensus about its magnetic and transport ground states. This work provides a detailed study of the magnetotransport properties of 300 nm CaRuO3 epitaxial films grown on single crystalline SrTiO3 and LaAlO3 substrates. The magnetic and electronic ground states in tensile strained CaRuO3/SrTiO3 films and compressively strained CaRuO3/LaAlO3 films are found to be distinctly different. In particular, in zero magnetic field, the high-temperature resistivity of both films show a T1/2 non-Fermi liquid behavior. Cooling below 30 K, CaRuO3/SrTiO3 undergoes metal–insulator-transition ascribed by 3D weak localization, with signs of weak ferromagnetic-like domains. By contrast, the transport data of the nonmagnetic CaRuO3/LaAlO3 film below 30 K, show T3/2 non-Fermi liquid type behavior. Magnetoresistance in CaRuO3/SrTiO3 shows combination of weak antilocalization and weak localization behaviors deep in the insulating side, emphasizing the existence of spin–orbit coupling and the strong influence of ferromagnetic impurities. Moreover, the nonlinearity signals in CaRuO3/SrTiO3 Hall measurements could be described by anomalous Hall effects. Interestingly, below 30 K, magnetoresistance and Hall in CaRuO3/LaAlO3 change sign, indicating an inversion from hole-like to electron-like behavior. We discuss the sensitivity of the 300 nm CaRuO3/SrTiO3 and CaRuO3/LaAlO3 films to the 30 K temperature, an additional quantum critical feature to the ruthenate oxides.

The morphology of an electrocatalyst has a crucial impact on its catalytic activity by enhancing the exposure of catalytically active sites [ 1]. Two-dimensional materials (2D) with layered structure have great potential in renewable energy applications. Such layered structures offer enlarged surface area, quick charge conduction, quantum effect, improved optical properties, and appreciable mechanical strength for superior electrocatalysis and photovoltaic applications. In this study, we introduced Ti₃C₂T_x MXene as an additive to the bulk graphitic carbon nitride g-C₃N₄. The g-C₃N₄ /Ti₃C₂T_x composite synthesized by a facile approach is strongly coupled with each other and exhibits more dense morphology with smooth layered surface. The coupling of the 2D architectures facilitates quick charge mobility at the interfaces and improves the ORR activity. Therefore, it is crucial to consider the synthesis, composition, and morphology of cost-effective electrocatalysts with low over potential and quick kinetics.

Mixed (FAPbI3)₀.₉₂(MAPbBr3)₀.₀₈ perovskite thin films exhibit strong nonlinear optical responses, rendering them promising candidates for applications in photonics and optical communications. In this work, we present a systematic study on the ultrafast third-order nonlinear optical processes in mixed perovskite nanocrystals (NCs) by exploring the generation of third harmonic radiation and giant two-photon absorption-based photoluminescence (PL) when excited by femtosecond laser pulses of a 1030 nm central wavelength. A comparative analysis of the coherent third harmonic generation in the thin-film-containing perovskite nanocrystals has shown a 40× enhancement of the third harmonic signal compared to the signal generated in the pure quartz substrate. The cubic dependence of the third-nonlinear optical response of the (FAPbI₃)₀.₉₂(MAPbBr₃)₀.₀₈ perovskites on the intensity of the driving radiation was identified using broadband 38 femtosecond driving pulses. The positive nonlinear refractive index (γ = +1.4 × 10⁻¹² cm²·W⁻¹) is found to play an important role in improving the phase-matching conditions of the interacting pulses by generating a strong third order harmonic. The giant two-photon absorption (TPA)-assisted PL peak was monitored and a blue shift of the PL was obtained in the higher intensity range of the laser pulses, with the absorption coefficient β estimated to be~+7.0 cm·MW⁻¹ at a 1030 nm laser wavelength.

Three-dimensional mesoporous TiO₂ scaffolds of anatase phase possess inherent eximious optical behavior that is beneficial for photoelectrodes used for solar energy conversion applications. In this regard; substantial efforts have been devoted to maximizing the UV and/or visible light absorption efficiency; and suppressing the annihilation of photogenerated charged species; in pristine mesoporous TiO₂ structures for improved solar illumination conversion efficiency. This study provides fundamental insights into the use of Mxene functionalized mesoporous TiO₂ as a photoelectrode. This novel combination of Mxene functionalized TiO₂ electrodes with and without TiCl₄ treatment was successfully optimized to intensify the process of photon absorption; charge segregation and photocurrent; resulting in superior photoelectrode performance. The photocurrent measurements of the prepared photoelectrodes were significantly enhanced with increased contents of Mxene due to improved absorption efficiency within the visible region; as verified by UV–Vis absorption spectroscopy. The anatase phase of TiO₂ was significantly augmented due to increased contents of Mxene and postdeposition heat treatments; as evidenced by structural analysis. Consequently; an appreciable coverage of well-developed grains on the FTO surface was observed in SEM images. As such; these newly fabricated conductive mesoporous TiO₂ photoelectrodes are potential candidates for photoinduced energy conversion and storage applications.

Three-Dimensional mesoporous TiO2 scaffolds of anatase phase possess inherent eximious optical behavior that are beneficial in designing photoelectrodes for solar energy conversion applications. However, substantial efforts have been devoted in maximizing the UV and/or visible light absorption efficiency, and suppressing the annihilation of photogenerated charged species in pristine mesoporous TiO2 structure for improved solar illumination conversion efficiencies. This study provides the fundamental insights into Mxene functionalized mesoporous TiO2 as photoelectrode for the first time. This novel combination of Mxene functionalized TiO2 electrodes with and without TiCl4 treatments have been successfully optimized to intensify the process of photon absorption, charge segregation and photocurrent, resulting in superior photoelectrode performance. The photocurrent measurements of prepared photoelectrodes are significantly enhanced upon increased contents of Mxene due to improved absorption efficiency within the visible region as verified by UV–Vis absorption spectroscopy. Moreover, as evident through structural analysis, the anatase phase of TiO2 is well grown due to increased contents of Mxene and post-deposition heat treatments. Consequently, an appreciable coverage of well-developed grains on FTO surface observed in SEM images. Thereby, the newly fabricated conductive mesoporous TiO2 photoelectrodes are potential candidates for photoinduced energy conversion and storage purposes.