Construction of single tungsten/copper atom oxide supported on the surface of TiO2 for the higher activity of electrocatalytic water splitting and photodegradation of organic pollutant

Intense studies are being carried out on single atom catalysts that exhibit remarkable activity and selectivity. To enhance their catalytic abilities, one must have a thorough understanding of the properties of the single metal atom active site and its dynamics in the working state. Herein, we report single metal atom oxide (SMAO) (metal: W/Cu) anchored on TiO₂-rGO nanomaterials (SMAO-ED-TiO₂-rGO) by simple sonication process. It is efficient for the electrocatalytic hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and photocatalytic degradation of pharmaceutical pollutant. The uniform dispersion of the tungsten/copper metal atom oxide over a TiO₂-rGO materials is detected by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The SMAO-ED-TiO₂-rGO nanocatalyst has shown impressive HER/OER activity with an overpotential of 121/295 mV at (-)10 mA cm^-2 current density and the low Tafel slope of 96/60.3 mV dec^-1 in 1 M KOH solution. Further, SMAO-ED-TiO₂-rGO nanocatalyst was used for the photocatalytic degradation of ciprofloxacin (CF). After 60 min of UV light irradiation, the SMAO-ED-TiO₂-rGO nanocatalyst efficiently photodegraded 98.5% of CF while retaining its activity for five cycles. Superoxide radicals (O₂^•-) are found to be the main reactive species required in the photodegradation of CF, according to scavenger study of the SMAO-ED-TiO₂-rGO nanocatalyst for CF degradation.

Graphene coupled TiO2 photocatalysts for environmental applications: A review

Nanostructured photocatalysts have always offered opportunities to solve issues concerned with the environmental challenges caused by rapid urbanization and industrialization. These materials, due to their tunable physicochemical characteristics, are capable of providing a clean and sustainable ecosystem to humanity. One of the current thriving research focuses of visible-light-driven photocatalysts is on the nanocomposites of titanium dioxide (TiO₂) with carbon nanostructures, especially graphene. Coupling TiO₂ with graphene has proven more active by photocatalysis than TiO₂ alone. It is generally considered that graphene sheets act as an electron acceptor facilitating the transfer and separation of photogenerated electrons during TiO₂ excitation, thereby reducing electron-hole recombination. This study briefly reviews the fundamental mechanism and interfacial charge-transfer dynamics in TiO₂/graphene nanocomposites. Design strategies of various graphene-based hybrids are highlighted along with some specialized synthetic routes adopted to attain preferred properties. Importantly, the enhancing interfacial charge transfer of photogenerated e¯_CB through the graphene layers by morphology orientation of TiO₂, predominated exposure of their high energy crystal facets, defect engineering, enhancing catalytic sites in graphene, constructing dedicated architectures, tuning the nanomaterial dimensionality at the interface, and employing the synergism adopted through various modifications, are systematically compiled. Portraying the significance of these photocatalytic hybrids in environmental remediation, important applications including air and water purification, self-cleaning surfaces, H₂ production, and CO₂ reduction to desired fuels, are addressed.

A novel site-induced biomolecule anchoring strategy based on solid superacid ZrO2/SO42- for fabricating label-free IgG electrochemical immunosensors

In this work, a unique zirconium dioxide solid superacid (ZrO₂/SO₄²⁻) was utilized for the fabrication of an IgG electrochemical immunosensor.

Nitrogen-doped graphene quantum dots anchored on NiFe layered double-hydroxide nanosheets catalyze the oxygen evolution reaction

N-GQDs/NiFe-LDH layered nanosheet structure has excellent OER catalytic performance.

The one-pot synthesis of porous Ni0.85Se nanospheres on graphene as an efficient and durable electrocatalyst for overall water splitting

Ni_0.85Se/RGO composite exhibits extraordinary water splitting.