Photoelectrodes For Hydrogen Production Research Articles

Boost the photocatalytic hydrogen production of the nanocomposites conducting polypyrrole modified with metal oxide (CuO)

This study explores the use of a PPy/CuO nanocomposite films for photocatalytic hydrogen production from wastewater, which is a significant avenue for solar energy applications. The photocatalyst is prepared using a simple in situ polymerization method on a glass substrate, and is found to exhibit high photocatalytic H2 evolution activity without the need for any co-catalyst. The structure of the PPy and CuO components is confirmed through XRD, TEM, FTIR and XPS analyses. The SEM indicates that CuO nanoparticles cause a homogenous PPy morphology due to the reduction of the accumulation by incorporation of CuO in PPy. The composite is found to have optical absorption spectra covering the UV, Vis, and near IR regions, with a band gap of 1.92 eV making it suitable as a photoelectrode for hydrogen production. The effect of light/dark, on/off chopped light, and monochromatic wavelengths on the photocatalytic activity is studied, and the electrode is found to exhibit a strong response to light under different monochromatic wavelengths that match its optical absorbance behavior. The photocurrent density values obtained are 3.7, 3.4, 2.9, and 0.45 μA cm−2 under 340, 440, 540, and 730 nm, respectively. The study is low-cost and holds promise for the production of hydrogen gas from wastewater.

Impact of carbon nanotubes concentrations on the performance of carbon nanotubes/zinc oxide nanocomposite for photoelectrochemical water splitting

Under the influence of visible light, the photoelectrochemical (PEC) method of water splitting offers a green method for producing sustainable hydrogen. In this work, several volume ratios of carbon nanotubes (CNTs) were incorporated in the zinc oxide (ZnO) matrix to prepare ZnO/CNTs nanocomposites on a glass substrate as photoelectrodes for hydrogen production. These electrodes were synthesized via the spray pyrolysis technique and chemical vapor deposition. Various approaches were used to analyze the chemical composition, crystal structure, morphology, and optical properties of pure ZnO and ZnO/CNTs nanocomposites. The structural properties showed that crystallite size is decreased from 44.2 nm to 36.8 nm, and the optical shows that the energy bandgap (Eg) enhanced from 3.07 to 2.87 eV for pure ZnO and the optimum sample of ZnO/7 mL CNTs nanocomposite, respectively. The maximum photocurrent density (Jph) was found for the 7 mL CNTs among the produced ZnO/X CNTs nanostructures. The value of Jph for ZnO/7 mL CNTs (200.7 µA/cm2) is around 33 times greater compared with pure ZnO (6.96 µA/cm2). At 490 nm, the incident photon-to-current efficiency (IPCE) of ZnO/7 mL CNTs is roughly 9.85 %. The ZnO/CNTs photoelectrode showed a hydrogen evolution rate of 4.34 mmole/h.cm2. The improved photoelectrode additionally exhibits strong chemical stability and a lengthy lifetime under visible light without photo-corrosion. Finally, the electrochemical impedance spectroscopy and the PEC water-splitting mechanism for ZnO/CNTs were discussed. This study presents a simple method that enables the fabrication of inexpensive and efficient ZnO/CNTs photoelectrode for renewable energy applications.

CuO-TiO2 nanostructures prepared by chemical and electrochemical methods as photo electrode for hydrogen production

In present study, copper (II) oxide (CuO) nanostructures were separately synthesized via chemical and electrochemical methods. CuO were coated with chemically synthesized titanium dioxide (TiO2). Morphological and structural properties of CuO and TiO2 coated CuO (CuO-TiO2) materials were examined via field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). FESEM images showed that nanowire like CuO formed at both chemical and electrochemical techniques. TiO2 nanoparticles were homogenously distributed all over CuO surfaces. XRD pattern revealed CuO has monoclinic crystal structure with metallic Cu. Moreover, rutile TiO2 crystallized in the tetragonal crystal structure. Electrochemical impedance spectroscopy (EIS) and potentiodynamic (PD) polarization measurements were utilized to study electro catalytic performance of the materials towards hydrogen evolution reaction (HER). The values of both energy consumption, and energy efficiency were determined as 329.43 kJ mol−1 and 86.0% at −50 mA cm−2 current density for HER on electrochemically synthesized CuO-TiO2 at 25 °C.

Amorphous silicon carbide photoelectrode for hydrogen production directly from water using sunlight

Results on the use of amorphous silicon carbide (a-SiC:H) as a photoelectrode in an integrated ‘hybrid’ photoelectrochemical (PEC) cell to produce hydrogen directly from water using sunlight are presented. A high quality a-SiC:H thin film with bandgap >2.0eV was fabricated by RF-PECVD technique using a SiH4, H2 and CH4 gas mixture. Incorporation of the carbon in the a-SiH film not only increased the bandgap, but also led to an increase in corrosion resistance in an electrolyte. Adding H2 during the fabrication process led to a decrease in the density of states (DOS) in the films. Immersing the a-SiC:H(p)/a-SiC:H(i) structure in a pH 2 electrolyte showed excellent durability up to 100 h (so far tested); the photocurrent increased and the photocurrent onset shifted anodically after the 100-h durability test, which is encouraging. It was also found that a SiO x layer is formed on the surface of a-SiC:H when exposed to air, which led to a decrease in the photocurrent, and the photocurrent onset shifted cathodically. We have found that this effect could be removed via a hydrofluoric acid dip and the photocurrent could be increased to over 6mA/cm2 at a potential of −1.4V (versus Ag/AgCl). To boost the photovoltage (potential) required for water splitting, the configuration of a-Si:H tandem (or ‘micromorph’)/a-SiC:H structure (PV/PEC) could be viable for water splitting. As a first step, we integrated amorphous silicon tandem solar cells with an a-SiC:H photoelectrode, which exhibited encouraging results. Finally, via simulation, we showed that using a-SiC:H as a photoelectrode could lead to a solar-to-hydrogen (STH) conversion efficiency >10%.

Preparation and characterization of (Zn,Cd)S photoelectrodes for hydrogen production

The authors report the preparation and characterization of (Zn,Cd)S (ZCS) photoelectrodes for hydrogen and oxygen production in a photoelectrolytic cell. ZCS photoelectrodes were prepared by mixing CdS and ZnS powders and sintering at high temperature in the presence of CdCl 2, as the flux. In some cases the ZCS was loaded with Mo during the preparation. These mixtures were characterized by structural analysis using X-ray diffraction (XRD), photosensitivity measurements in artificial light (halogen and xenon lamps)in solid state, and in a 0.1 M solution of Na 2SO 3. The results indicate that a screen printed CdS–ZnS mixture possesses high photosensitivity for its application as photocatalysts for water electrolysis.