Shazrah Shahzad

This review highlights advances in nanostructured transition metal catalysts supported on nickel foam, spanning rational design to high-performance alkaline oxygen evolution.

Hydrogen production via seawater electrolysis offers great potential for clean energy; however, sluggish kinetics and corrosive ions hinder the efficiency. Hence, the fabrication of economically viable and robust electrocatalysts is essential for effective alkaline seawater splitting. Herein, Mo-doped CuS/NiS interfaces supported on nickel foam (Mo-CuS/NiS/NF) were designed using polyoxometalate-based metal-organic frameworks (POM-MOFs) through a scalable hydrothermal strategy for the electrocatalytic hydrogen evolution reaction (HER). The enhanced features provide exposed active sites and offer low overpotentials, leading to enhanced HER performance under alkaline seawater conditions. Experimental and theoretical analyses revealed successful Mo doping, the formation of dual transition-metal sulfide (TMS) interfaces, and a decreased Gibbs free energy (merely 0.08 eV for Mo-CuS and -0.70 eV for Mo-NiS) of the rate-determining step. Optimized Mo-CuS/NiS/NF required low overpotentials under alkaline (78 mV), simulated (95 mV), and real seawater conditions (111 mV), surpassing 20% Pt/C@NF at 10 mA cm^-2 while remaining stable for over 50 h. Therefore, Mo-doped CuS/NiS interfaces supported on NF provide a guideline for significant advancements in the synthesis of highly efficient POM-MOF-derived sulfide electrocatalysts for electrocatalytic water splitting with enhanced performance, stability, and practicality.

Reduced graphene oxide (rGO) has attracted enormous interest as a promising candidate material for gas detection due to its large specific surface areas. In our work, rGO films were fabricated on a large scale using dip-coating and spin-coating methods for the detection of nitrogen dioxide (NO₂) gas at room temperature. The influence of different test environments on the sensing performance, including the test atmosphere, gas flow and gas pressure was evaluated. The response time of the dip-coating method was 573 s with a long recovery period of 639 s and for the spin-coating method, the response time and recovery time was 386 s and 577 s, respectively. In addition, the spin-coated sensor exhibited high selectivity to NO₂, with the response increasing by more than 20% (for 15 ppm NO₂) as compared with that for HCHO, NH₃, and CH₄. Our results indicated that the spin coating method was more suitable for rGO-based gas sensors with higher performance.