SnO₂ aerogel/reduced graphene oxide (rGO) nanocomposites were synthesized using the sol–gel method. A homogeneous dispersion of graphene oxide (GO) flakes in a tin precursor solution was captured in a three-dimensional network SnO₂ aerogel matrix and successively underwent supercritical alcohol drying followed by the in situ thermal reduction of GO, resulting in SnO₂ aerogel/rGO nanocomposites. The chemical interaction between aerogel matrix and GO functional groups was confirmed by a peak shift in the Fourier transform infrared spectra and a change in the optical bandgap of the diffuse reflectance spectra. The role of rGO in 3D aerogel structure was studied in terms of photocatalytic activity with detailed mechanism of the enhancement such as electron transfer between the GO and SnO₂. In addition, the photocatalytic activity of these nanocomposites in the methyl orange degradation varied depending on the amount of rGO loading in the SnO₂ aerogel matrix; an appropriate amount of rGO was required for the highest enhancement in the photocatalytic activity of the SnO₂ aerogel. The proposed nanocomposites could be a useful solution against water pollutants.

It is challenging to develop scalable and stable multifunctional catalysts for energy storage and conversion applications. To address the above challenges, we designed 3D macroporous nanosandwich-like aerogels using an in situ sol-gel assembly for 2D g-C₃N₄ nanosheet-supported NiCo₂S₄ nanoporous aerogels. The resultant in situ method not only assembles NiCo₂S₄ but also 2D g-C₃N₄ into the sandwich-like 3D network, allowing rapid ion and electron transport. The potential of g-C₃N₄ and NiCo₂S₄ in electrochemical energy storage and electrocatalysis is promising for improving its electrochemical activities. The synthesized 3D NiCo₂S₄/g-C₃N₄ (3) composite aerogel electrode achieved a remarkable specific capacitance value, 1083Fg^-1 at 5mAcm^-2 current density with 87.03 cyclic stability. Furthermore, the asymmetric electrochemical supercapacitor device was fabricated with a maximum specific energy of 43Whkg^-1, with outstanding electrochemical stability of about 97 over 10,000 charge/discharge cycles. In addition, NiCo₂S₄/g-C₃N₄ (3) catalysts achieved 294 and 155mV as oxygen and hydrogen evolution reaction overpotentials, respectively, at 20 and 10mAcm^-2 current density values. This study provides a new method for the conversion of 2D sheets and 0D colloidal network into 3D macroporous nanocomposite aerogels in multifunctional applications.

Cost-effective alkaline water electrolysis requires non-precious-metal electrocatalysts that sustain the hydrogen evolution reaction (HER) at high current densities while maintaining favorable interfacial kinetics and an accessible electrode structure. Here, Co incorporation was used to suppress the long-range crystalline order of Fe and generate poorly crystalline Fe-Co aerogels through one-pot NaBH₄ reduction, gelation, and freeze-drying. A Fe_100−xCo_x series (x = 0, 60, 80, and 100; nominal feed compositions) was examined to determine how composition-induced structural changes affect network morphology, interfacial accessibility, and high-current HER behavior. Among the series, FeCo60-A formed the finest interconnected particle network and exhibited the largest BET surface area (34.1 m² g⁻¹), a high double-layer capacitance (1.04 mF cm⁻²), and the smallest apparent Nyquist arc. After iR correction, it required overpotentials of 345, 520, and 685 mV to reach 100, 500, and 1000 mA cm⁻², respectively, and maintained a nearly constant potential during 24 h operation at −1000 mA cm⁻² while largely retaining its interconnected porous morphology. These results demonstrate that Co incorporation into the Fe-based aerogel framework effectively tunes structural order and interfacial characteristics, enabling improved HER performance under high-current alkaline conditions.