Facile synthesis and application of nano-sized semiconductor metal oxides for optoelectronic devices have always affected fabrication challenges since it involves multi-step synthesis processes. In this regard, semiconductor oxides derived directly from metal–organic frameworks (MOFs) routes have gained a great deal of scientific interest owing to their high specific surface area, regular and tunable pore structures. Exploring the application potential of these MOF-derived semiconductor oxides systems for clean energy conversion and storage devices is currently a hot topic of research. In this study, titanium-based MIL-125(Ti) MOFs were used as a precursor to synthesize cobalt-doped TiO2-based dye-sensitized solar cells (DSSCs) for the first time. The thermal decomposition of the MOF precursor under an air atmosphere at 400 °C resulted in mesoporous anatase-type TiO2 nanoparticles (NPs) of uniform morphology, large surface area with narrow pore distribution. The Co2+ doping in TiO2 leads to enhanced light absorption in the visible region. When used as photoanode in DSSCs, a good power conversion efficiency (PCE) of 6.86% with good photocurrent density (Jsc) of 13.96 mA cm−2 was obtained with the lowest recombination resistance and the longest electron lifetime, which is better than the performance of the pristine TiO2-based photoanode.

Herein, we report a simple hydrothermal synthesis of ZnO-Ti3C2 MXene nanocomposites with a varying wt % of ZnO to exploit the synergistic effect of 2D layer structured Ti3C2 and semiconductor ZnO for photocatalysis and electrocatalysis applications. A systematic study on the efficiency of ZnO-Ti3C2 nanocomposites toward the degradation of organic pollutants (dyes and pharmaceuticals) and the hydrogen evolution reaction (HER) is demonstrated. Among the developed nanohybrid catalysts, the ZnO-Ti3C2 composite with 10 wt % ZnO (MXZnO-10) showed the highest photodegradation efficiency of 76.4% within 10 min of the reaction and 99.2% in 60 min for methylene blue (MB) dye. The synergistic interactions between 2D layered Ti3C2 and ZnO improved the lifetime of electrons and holes by reducing the recombination rate. The uncombined electrons and holes facilitated the effective degradation of the MB dye. The ZnO-Ti3C2 nanocomposite with 5 wt % ZnO (MXZnO-5) showed excellent HER performance and exhibited an overpotential of 495 mV at 10 mA/cm2 with a Tafel slope of 108 mV/dec. This work widens the application range of transition metal oxide–MXene composites, providing potential substitute materials for photocatalysis and electrocatalysis applications.

Due to their chemical and electrical characteristics, such as metallic conductivity, redox-activity in transition metals, high hydrophilicity, and adjustable surface properties, MXenes are emerging as important contributors to oxygen reduction...

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Metal–air batteries have attracted significant attention due to their excellent advantage of high-energy-density metal anodes with air cathodes. The development of structurally stable materials has been a great challenge for Zn-air batteries. Layered 2D materials provide unique opportunities due to their facial synthesis and structural stability. In this presentation, we demonstrate intercalated architecture TaSi2N4 layered material for cathode and anode of Zn–air batteries. The mechanistic aspects of Zn storage will be shown. These van der Waals materials undergo a phase during Zn loading. Interestingly, TaSi2N4 surface shows the two-electron mechanism of oxygen reduction. These layered materials will create new possibilities for the development of unique electrodes of Zn–air batteries.