Photoelectrochemical water splitting is a promising route for the renewable production of hydrogen fuel. This work presents the results of a technical and economic feasibility analysis conducted for ...four hypothetical, centralized, large-scale hydrogen production plants based on this technology. The four reactor types considered were a single bed particle suspension system, a dual bed particle suspension system, a fixed panel array, and a tracking concentrator array. The current performance of semiconductor absorbers and electrocatalysts were considered to compute reasonable solar-to-hydrogen conversion efficiencies for each of the four systems. The U.S. Department of Energy H2A model was employed to calculate the levelized cost of hydrogen output at the plant gate at 300 psi for a 10 tonne per day production scale. All capital expenditures and operating costs for the reactors and auxiliaries (compressors, control systems,
etc.
) were considered. The final cost varied from $1.60$10.40 per kg H
2
with the particle bed systems having lower costs than the panel-based systems. However, safety concerns due to the cogeneration of O
2
and H
2
in a single bed system and long molecular transport lengths in the dual bed system lead to greater uncertainty in their operation. A sensitivity analysis revealed that improvement in the solar-to-hydrogen efficiency of the panel-based systems could substantially drive down their costs. A key finding is that the production costs are consistent with the Department of Energy's targeted threshold cost of $2.00$4.00 per kg H
2
for dispensed hydrogen, demonstrating that photoelectrochemical water splitting could be a viable route for hydrogen production in the future if material performance targets can be met.
This work describes the design and technoeconomics of four conceptual water splitting reactors based on particle suspensions and panel electrodes.
A cobalt-phosphate based oxygen evolution catalyst (Co-Pi OEC) was electrochemically deposited onto the surface of a porous bismuth vanadate electrode doped with 2 atom% Mo (BiV0.98Mo0.02O4). The ...porous BiV0.98Mo0.02O4 electrode was prepared using a surfactant assisted metal-organic decomposition technique at 500 degreeC. The comparison of the photocurrent-voltage characteristics of the BiV0.98Mo0.02O4 electrodes with and without the presence of Co-Pi catalyst demonstrated that the Co-Pi catalyst enhanced the anodic photocurrent of the BiV0.98Mo0.02O4 electrode with its effect more pronounced at lower potentials. A stable photocurrrent density of 1.0 mA cm-2 at 1.0 V vs. Ag/AgCl was achieved under standard AM 1.5 illumination using 0.5M Na2SO4 aqueous solution in phosphate buffer at pH7. Relative to the BiV0.98Mo0.02O4 electrode, a sustained enhancement, nearly doubled photocurrent density was observed at 1.0 V vs. Ag/AgCl for Co-Pi/BiV0.98Mo0.02O4 composite photoelectrode. Significant performance gains are obtained on BiV0.98Mo0.02O4 electrodes upon modification with Co-Pi water oxidation catalyst.
Achieving high solar-to-hydrogen (STH) efficiency concomitant with long-term durability using low-cost, scalable photo-absorbers is a long-standing challenge. Here we report the design and ...fabrication of a conductive adhesive-barrier (CAB) that translates >99% of photoelectric power to chemical reactions. The CAB enables halide perovskite-based photoelectrochemical cells with two different architectures that exhibit record STH efficiencies. The first, a co-planar photocathode-photoanode architecture, achieved an STH efficiency of 13.4% and 16.3 h to t
, solely limited by the hygroscopic hole transport layer in the n-i-p device. The second was formed using a monolithic stacked silicon-perovskite tandem, with a peak STH efficiency of 20.8% and 102 h of continuous operation before t
under AM 1.5G illumination. These advances will lead to efficient, durable, and low-cost solar-driven water-splitting technology with multifunctional barriers.
Nanostructured Si eliminates several critical problems with Si photocathodes and dramatically improves a photoelectrochemical (PEC) reaction important to water-splitting. Our nanostructured black Si ...photocathodes improve the H2 production by providing (1) near-ideal anti-reflection that enables the absorption of most incident light and its conversion to photogenerated electrons and (2) extremely high surface area in direct contact with water that reduces the overpotential needed for the PEC hydrogen half-reaction. Application of these advances would significantly improve the solar H2 conversion efficiency of an ideal tandem PEC system. Finally, the nanostructured Si surface facilitates bubble evolution and therefore reduces the need for surfactants in the electrolyte.
The 2022 solar fuels roadmap Segev, Gideon; Kibsgaard, Jakob; Hahn, Christopher ...
Journal of physics. D, Applied physics,
08/2022, Letnik:
55, Številka:
32
Journal Article
Recenzirano
Odprti dostop
Abstract
Renewable fuel generation is essential for a low carbon footprint economy. Thus, over the last five decades, a significant effort has been dedicated towards increasing the performance of ...solar fuels generating devices. Specifically, the solar to hydrogen efficiency of photoelectrochemical cells has progressed steadily towards its fundamental limit, and the faradaic efficiency towards valuable products in CO
2
reduction systems has increased dramatically. However, there are still numerous scientific and engineering challenges that must be overcame in order to turn solar fuels into a viable technology. At the electrode and device level, the conversion efficiency, stability and products selectivity must be increased significantly. Meanwhile, these performance metrics must be maintained when scaling up devices and systems while maintaining an acceptable cost and carbon footprint. This roadmap surveys different aspects of this endeavor: system benchmarking, device scaling, various approaches for photoelectrodes design, materials discovery, and catalysis. Each of the sections in the roadmap focuses on a single topic, discussing the state of the art, the key challenges and advancements required to meet them. The roadmap can be used as a guide for researchers and funding agencies highlighting the most pressing needs of the field.
Herein, we demonstrate greatly improved conversion of CO2 using a gas diffusion electrode (GDE) with flowing electrolyte configuration for CO2 gas delivery in combination with a high surface area ...nickel phosphide electrocatalyst. This configuration achieves 40–50% selectivity for total carbon products over H2 formation (HER) at total current densities ranging from 50 to 300 mA cm−2. We developed a soft-templating method using CTAB detergent micelles for synthesis of phase-pure Ni2P, achieving a 260-fold larger surface area (BET) and porous sponge-like morphology that produces stable currents. This catalyst produces mainly one C-product, methylglyoxal (MG, C3H4O2) with 38–47% overall selectivity, the highest reported selectivity for a 12-electron reduction product. The versatile soft-templating method for electrocatalyst synthesis uses low-temperature (185 °C) that is permissive for incorporation of co-catalysts that are otherwise destroyed by the high temperatures used in traditional solid-state synthesis (SSS). The non-porous Ni2P-SSS catalyst produces mainly H2 at these current densities. Achieving these high currents and C/H selectivity benefits from use of hydrophobic polymers as co-catalyst binders (cationic = Nafion, anionic = PFAEM and neutral = PTFE) to improve CO2 conversion. PFAEM is the better ionomer for the CO2RR at high current density, postulated as due to suppressing CO2 conversion to inactive bicarbonate. Precipitation of the carbon products as a polycarbonate polymer occurs at high currents.
Gallium indium phosphide (GaInP2) is a semiconductor with promising optical and electronic properties for solar water splitting, but its surface stability is problematic as it undergoes significant ...chemical and electrochemical corrosion in aqueous electrolytes. Molybdenum disulfide (MoS2) nanomaterials are promising to both protect GaInP2 and to improve catalysis because MoS2 is resistant to corrosion and also possesses high activity for the hydrogen evolution reaction (HER). In this work, we demonstrate that GaInP2 photocathodes coated with thin MoS2 surface protecting layers exhibit excellent activity and stability for solar hydrogen production, with no loss in performance (photocurrent onset potential, fill factor, and light-limited current density) after 60 h of operation. This represents a 500-fold increase in stability compared to bare p-GaInP2 samples tested in identical conditions.
Earth-abundant copper-barium-thiostannate Cu2BaSnS4 (CBTS)-based thin films have recently been reported to exhibit the optoelectronic and defect properties suitable as absorbers for ...photoelectrochemical (PEC) water splitting and the top cell of tandem photovoltaic solar cells. However, the photocurrents of CBTS-based PEC devices are still much lower than the theoretical value, partially due to ineffective charge collection at CBTS/water interface and instability of CBTS in electrolytes. Here, we report on overcoming these issues by employing overlayer engineering. We find that CdS/ZnO/TiO2 overlayers can significant-ly improve the PEC performance, achieving saturated cathodic photocurrents up to 7.8 mA cm-2 at the potential of -0.10 V versus reversible hydrogen electrode (RHE) in a neutral electrolyte solution, which is much higher than the best bare CBTS film attaining a photocurrent of 4.8 mA cm-2 at the potential of -0.2 V versus RHE. Finally, our results suggest a viable approach for improving the performance of CBTS-based PEC cells.
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