Water-Splitting Artificial Leaf Based on a Triple-Junction Silicon Solar Cell: One-Step Fabrication through Photoinduced Deposition of Catalysts and Electrochemical Operando Monitoring

Abstract

Solar hydrogen generation via water splitting using a monolithic photoelectrochemical cell, also called artificial leaf, could be a powerful technology to accelerate the transition from fossil to sustainable energy sources. Identification of scalable methods for the fabrication of monolithic devices and gaining insights into their operating mode to identify solutions to improve performance and stability represent great challenges. Herein, we report on the one-step fabrication of a CoWO|ITO|3jn-a-Si|Steel|CoWS monolithic device via the simple photoinduced deposition of CoWO and CoWS as oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) catalyst layers, respectively, onto an illuminated ITO|3jn-a-Si|Steel solar cell using a single-deposition bath containing the [Co­(WS4)2]2– complex. In a pH 7 phosphate buffer solution, the best device achieved a solar-to-hydrogen conversion yield of 1.9%. Evolution of the catalyst layers and that of the 3jn-a-Si light-harvesting core during the operation of the monolithic device are examined by conventional tools such as scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES) together with a bipotentiostat measurement. We demonstrate that the device performance degrades due to the partial dissolution of the catalyst. Still, this degradation is healable by simply adding [Co­(WS4)2]2– to the operating solution. However, modifications on the protecting indium-doped tin oxide (ITO) layer are shown to initiate irreversible degradation of the 3jn-a-Si light-harvesting core, resulting in a 10-fold decrease of the performances of the monolithic device.

Solar Panel Technologies for Light-to-Chemical Conversion

“…The artificial leaf design was experimentally demonstrated by sandwiching a triple-junction amorphous silicon solar cell between NiMoZn and Co-based catalysts. , Ever since, a broad community has started developing integrated devices, expanding this concept to a wide range of light absorbers in PEC or PV–PEC configurations. Despite solar-to-hydrogen conversion efficiencies reaching beyond 3% for water splitting (Table ), CO 2 reduction posed challenges for artificial leaf devices using only two light absorbers.…”

“…The distinct thermodynamic requirements of organics oxidation and O 2 evolution may demand a single or tandem light absorber configuration, whereas the starting material could be more suitable for a layered or particulate panel. 15,16 Ever since, a broad community has started developing integrated devices, 24 expanding this concept to a wide range of light absorbers in PEC or PV−PEC configurations. Despite solar-to-hydrogen conversion efficiencies reaching beyond 3% for water splitting (Table 1), 25 CO 2 reduction posed challenges for artificial leaf devices using only two light absorbers.…”

Electrocatalytic H2 evolution using binuclear cobalt complexes as catalysts

“…Indeed, overpotential ( η ) is a key descriptor to appreciate a H 2 -evolution catalyst and compare one to others. It can be deduced from the onset potential, being the potential where the H 2 evolution starts to emerge, 27 the potential required to sustain a given catalytic current density, 27 or the half-wave potential of the catalytic wave. 28 Herein, the overpotential required for the H 2 evolution when using both catalysts 1 and 2 in DMF solution is determined at the half-way potential in the presence of 60 mM concentration of acetic acid.…”

Porous silicon-nanowire-based electrode for the photoelectrocatalytic production of hydrogen

“…The system was illuminated with a parallel beam from a Newport xenon lamp set at 280 W passing through an AM 1.5 filter and tuned to 100 mW cm −2 to simulate closely the illumination of 1 Sun, and calibrated before each test with a silicon photodiode at the working electrode position. 38 The current density–potential ( J – V ) polarization curve was measured via a linear sweep voltammetry from 0.2 V to −0.5 V vs. RHE. Current density–time ( I – t ) curve was measured via a chronoamperometry at −0.15 V vs. RHE for at least 1 hour with N 2 bubbling or in a tightly closed environment after N 2 degas for 20 minutes.…”