Synthesis of Sulfur-Encapsulated Mullite Structure Bi0/Fe0-Rich Bi2Fe4O9-x Framework by Advanced Probe Sonic Approach Applied for Augmented Electroactive Hydrogen Production, Storage and Photoactive Degradation Studies

A new series of dual Bi0/Fe0-rich in sulfur-encapsulated BFNPs (SBFNPs-framework) with a sulfur content ranging from 1.0% to 3.0% were prepared using an advanced probe-sonic approach. The SBFNPs-framework with a sulfur content of 2.0% exhibited a maximum methylene-blue (MB) photo-degradability of 84.20% at 120 minutes of visible-light exposure. The MB degradation rate of the SBFNPs-framework (0.00839 min-1) was faster than that of pure-BFNPs (0.00308 min-1). Furthermore, the electro-catalyst of SBFNPs-framework demonstrated remarkable hydrogen-production activity, as indicated by a low over-potential (204 mV), a small Tafel-slope (69 mV/dec), a higher double-layer-capacitance (142.0 mF/cm2), a larger electro-chemically-active-surface-area (40.6 cm2), a plentiful presence of catalytic-active-sites (5.65 ×10-7 mol/cm2), and excellent stability, respectively. Also, the hydrogen-storage capacity of the SBFNPs-framework exhibited a maximum discharge capacity of 717.35 mAhg-1 and a hydrogen-storage capacity of 2.66 wt.% at a 2.0% sulfur content. These findings have great potential implications for future energy storage and environmental applications.