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Designing and developing noble-metal-free catalysts are of current interest in clean hydrogen generation via water splitting. As carbonaceous species are ideal choices as templates for various electrocatalysis, an improved synthetic route and an in-depth understanding of their electrochemical performance are essential. Herein, we have investigated the catalytic performance of rGO-encapsulated Mn and V mixed oxide hybrid structures (MVG) on a NiFeP matrix, focusing on their potential for catalyzing hydrogen evolution in an alkaline environment. The hierarchical MVG hollow microspheres hybrids are synthesized via a simple one-step in situ solvothermal method and MVG/NiFeP coatings are developed by facile electroless plating technique. As evidenced from the X-ray photoelectron spectroscopy, the multiple redox active sites in the 3d-band of Mn and V in MVG hybrid structural coatings serve as electron pumps, and rGO facilitates electronic conductions during catalytic reactions. The modulated electronic structure and strong synergistic effects between NiFeP and MVG facilitate rapid electron transfer kinetics, and the hybrids demonstrate superior HER performance. Consequently, the structural hybrid coatings possess an enhanced electronic conducting path (lower RCT= 545.3 Ω) and large ECSA values with a lower overpotential of 85 mV at 10 mA cm–2and a reduced Tafel slope of 64.1 mV dec–1with Volmer–Heyrovsky mechanism in alkaline media.

Zinc ferrite pigments have emerged as potential candidates for enabling technology for large-scale energy-saving applications, which are safer, more accessible, and less damaging to the environment when compared to similar rare-earth-based colorants. Introducing transition metals into the ZnFe2O4host lattice may distort the normally ordered lattice. A mineralizer was employed to further tune the color and infrared (IR)-reflective properties. NaCl lowered the crystallization temperature of the spinel zinc ferrite phase owing to its facilitation of ionic diffusion in solid-state reactions. Using a mineralizer promoted the generation of regular pigment particles to further enhance the optical property, leading to a low-cost, effective green strategy for heat mitigation. The acrylic coating of the pigment over the concrete substrate demonstrated good color consistency and near infrared (NIR) reflectivity (temperature shielding character). The surface temperature difference between the coated and uncoated acrylic binder-based mineralizer-added zinc ferrite was 16.4 °C. Since the synthesized zinc ferrite-based pigments have chemical stability and good NIR reflectivity and color characteristics, they have potential application for exterior energy-saving coatings.

The approach for promoting the tunable photochemical properties of NiMOF for catalytic applications has been recognized as a smart choice for solar water splitting. However, the major concern is the low specific surface area (SSA). The present approach has specifically resolved this problem by tuning the nature of the surface of NiMOF by anchoring with ultranano-sized CeO2. The CeO2(111) plane has a strong electron migrating affinity, and hence, the heterojunction significantly facilitates and directs the photoinduced electrons toward the reaction centers. In addition, the existence of NiMOF with switchable valence states as catalytic centers in the heterojunction also efficiently catalyzes the proton reduction. The enhancement in SSA of NiMOF and the surface tuning with ultranano-sized CeO2are the key reasons for the observed higher activity (2.14 mmol/g/h) of the 0.2:1-CeO2@NiMOF hybrid composite with a high AQE value (18.82% at 320 nm). The results obtained are compared and found to be highly competitive with respect to high standard recent reports.