Enhanced solar hydrogen generation using Cu-Cu2O integrated polypyrrole nanofibers as heterostructured catalysts

Nanostructured conducting polymeric materials are beneficial for electron conduction and mass transport, showing prominent photocatalytic performance for dye degradation under visible light. Herein, we report a simple colloidal route for large-scale synthesis of copper and copper oxides (Cu2O) modified polypyrrole nanofibers (PPy) heterostructures, which demonstrate significantly high performance towards H2 generation under visible light. The presence of Cu nanoparticles (NPs) of 50 nm and cubic shaped Cu2O nanoparticles of size ~200 nm endows the heterostructures with a large specific surface area as well as good dispersion of nanoparticles on PPy nanofibers allows the migration of electron during catalysis. The UV-Visible diffuse reflectance spectra displayed strong absorption in the visible region, which favors the photocatalytic performance. Under visible light irradiation, Cu2O/PPy exhibits excellent H2 production with the rate of 67 mmol h−1 which is ~12 times higher than PPy (5.7 mmol h–1). The optimal catalyst Cu/PPy-0.05 exhibits the high hydrogen generation rate of ~ 50 mmol h–1, which reaches 8.6 times of pure PPy. The Mott–Schottky plot revealed that photo generated charge carrier concentration has been increased considerably for Cu2O/PPy (2.791013cm3) compare to pure PPy (1.431011 cm3). The high-performance Cu2O/PPy catalyst provides a fervent alternative to noble metal-based catalysts for the hydrogen generation in practical applications

Influence of Gold Nanoparticles on the Nonlinear Optical and Photoluminescence Properties of Eu2O3 Doped Alkali Borate Glasses

Alkali borate glasses activated with trivalent europium ions and rooted with gold (Au) nanoparticles (NPs) were synthesised through a melt quenching process involving a selective thermochemical reduction and their applicability as photonic materials was assessed in detail. Non-linear optical (NLO) measurements were performed using a Z-scan approach in the wavelength range of 700-1000 nm. The open aperture Z-scan signatures for the Eu3+-containing glasses embedded with and without the Au NPs established a reverse saturable absorption (RSA) at all of the studied wavelengths ascribed to the two-photon absorption (2PA). Surprisingly, the nonlinear optical absorption switched to a saturable absorption (SA) with an increase in the concentration of AuCl3. With the incorporation of the Au NPs, the UV excited photoluminescence (PL) intensity of the Eu3+-doped glasses increased first as a consequence of the local field enhancement by the Au NPs, and subsequently decreased at a higher concentration of AuCl3 due to the reverse energy transfer from the Eu3+ ion to the Au0 NPs. The electronic polarization effect of the host glass enhanced the 5D0→7F4 transition intensity on the incorporation of the gold NPs owing to the gold NP-embedded glasses showing a deep-red emission. The NLO and PL studies suggested that the investigated glasses containing a 0.01 mol% of AuCl3 is practically appropriate for photonic application

Influence of gold nanoparticles on the nonlinear optical and photoluminescence properties of Eu2O3 doped alkali borate glasses

Alkali borate glasses activated with trivalent europium ions and rooted with gold (Au) nanoparticles (NPs) were synthesised through a melt quenching process involving a selective thermochemical reduction and their applicability as photonic materials was assessed in detail. Non-linear optical (NLO) measurements were performed using a Z-scan approach in the wavelength range of 700-1000 nm. The open aperture Z-scan signatures for the Eu3+-containing glasses embedded with and without the Au NPs established a reverse saturable absorption (RSA) at all of the studied wavelengths ascribed to the two-photon absorption (2PA). Surprisingly, the nonlinear optical absorption switched to a saturable absorption (SA) with an increase in the concentration of AuCl3. With the incorporation of the Au NPs, the UV excited photoluminescence (PL) intensity of the Eu3+-doped glasses increased first as a consequence of the local field enhancement by the Au NPs, and subsequently decreased at a higher concentration of AuCl3 due to the reverse energy transfer from the Eu3+ ion to the Au-0 NPs. The electronic polarization effect of the host glass enhanced the D-5(0) -> F-7(4) transition intensity on the incorporation of the gold NPs owing to the gold NP-embedded glasses showing a deep-red emission. The NLO and PL studies suggested that the investigated glasses containing a 0.01 mol% of AuCl3 is practically appropriate for photonic applications