RESUMEN
Hydrogen production through direct sunlight-driven water splitting in photo-electrochemical cells (PECs) is a promising solution for energy sourcing. PECs need to fulfill three criteria: sustainability, cost-effectiveness and stability. Here we report an efficient and stable photocathode platform for H2 evolution based on Earth-abundant elements. A p-type silicon surface was protected by atomic layer deposition (ALD) with a 15 nm TiO2 layer, on top of which a 300 nm mesoporous TiO2 layer was spin-coated. The cobalt diimine-dioxime molecular catalyst was covalently grafted onto TiO2 through phosphonate anchors and an additional 0.2 nm ALD-TiO2 layer was applied for stabilization. This assembly catalyzes water reduction into H2 in phosphate buffer (pH 7) with an onset potential of +0.47 V vs. RHE. The resulting current density is -1.3 ± 0.1 mA cm-2 at 0 V vs. RHE under AM 1.5 solar irradiation, corresponding to a turnover number of 260 per hour of operation and a turnover frequency of 0.071 s-1.
RESUMEN
Metal organic {Ni4O4} clusters, known oxidation catalysts, have been shown to provide a valuable route in increasing the photocurrent response on silicon nanowire (SiNW) photocathodes. {Ni4O4} clusters have been paired with SiNWs to form a new photocathode composite for water splitting. Under AM1.5 conditions, the combination of {Ni4O4} clusters with SiNWs gave a current density of -16 mA/cm², which corresponds to an increase in current density of 60% when compared to bare SiNWs. The composite electrode was fully characterised and shown to be an efficient and stable photocathode for water splitting.
RESUMEN
Native diatoms made of amorphous silica are first converted into silicon structures via magnesiothermic process, preserving the original shape: electron force microscopy analysis performed on silicon-converted diatoms demonstrates their semiconductor behavior. Wet surface chemical treatments are then performed in order to enhance the photoluminescence emission from the resulting silicon diatoms and, at the same time, to allow the immobilization of biological probes, namely proteins and antibodies, via silanization. We demonstrate that light emission from semiconductive silicon diatoms can be used for antibody-antigen recognition, endorsing this material as optoelectronic transducer.
RESUMEN
Porous biosilica from diatom frustules is well known for its peculiar optical and mechanical properties. In this work, gold-coated diatom frustules are used as low-cost, ready available, functional support for surface-enhanced Raman scattering. Due to the morphology of the nanostructured surface and the smoothness of gold deposition via an electroless process, an enhancement factor for the p-mercaptoaniline Raman signal of the order of 10(5) is obtained.
RESUMEN
The performance of silicon for water oxidation and hydrogen production can be improved by exploiting the antireflective properties of nanostructured silicon substrates. In this work, silicon nanowires were fabricated by metal-assisted electroless etching of silicon. An enhanced photocurrent density of -17 mA/cm² was observed for the silicon nanowires coated with an iron sulphur carbonyl catalyst when compared to bare silicon nanowires (-5 mA/cm²). A substantial amount of 315 µmol/h hydrogen gas was produced at low bias potentials for the silicon nanowires coated with an iron sulphur carbonyl catalyst.
RESUMEN
The conversion of titania (TiO2) nanotubes into titanium (Ti), while preserving their nanotubular structures, is demonstrated. Their application as bone implants and electrodes for combined local drug delivery and electrical stimulation therapy is proposed.
RESUMEN
An effective solar-powered silicon device for hydrogen production from water splitting is a priority in light of diminishing fossil fuel vectors. There is increasing demand for nanostructuring in silicon to improve its antireflective properties for efficient solar energy conversion. Diatom frustules are naturally occurring biosilica nanostructures formed by biomineralizing microalgae. Here, we demonstrate magnesiothermic conversion of boron-doped silica diatom frustules from Aulacoseira sp. into nanostructured silicon with retention of the original shape. Hydrogen production was achieved for boron-doped silicon diatom frustules coated with indium phosphide nanocrystal layers and an iron sulfur carbonyl electrocatalyst.
RESUMEN
In the quest for solutions to meeting future energy demands, solar fuels play an important role. A particularly promising example is photocatalysis since even incremental improvements in performance in this process are bound to translate into significant cost benefits. Here, we report that semiconducting and high surface area 3D silicon replicas prepared from abundantly available diatom fossils sustain photocurrents and enable solar energy conversion.