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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

All-Perovskite Tandem Photoelectrodes for Unassisted Solar Hydrogen Production

Unassisted solar water splitting by multi-junction tandem photoelectrodes is a sustainable approach to generating green hydrogen fuels. Here, we report on the fabrication of monolithically integrated all-perovskite tandem photocathodes for efficient unassisted solar water splitting. All-perovskite tandem photocathodes wired to an iridium oxide anode deliver a high photovoltage of more than 2 V with an operating photocurrent density of 12.5 mA cm -2 at zero applied bias under simulated AM1.5G one sun illumination, yielding a solar-to-hydrogen (STH) conversion efficiency of 15%. The tandem photoelectrode demonstrates continuous operation for more than 120 hours in water under simulated one-sun illumination with less than 5% efficiency loss. A technoeconomic analysis shows the projected production cost of all-perovskite tandem photoelectrodes is $\$30$ m -2 , promising a levelized cost of hydrogen of less than $\$1$/kg if sufficient device longevity is realized. Finally, this work provides a path toward achieving cost-effective unassisted solar hydrogen fuel production.

08 HYDROGEN↗
NASA NTRS1977

Solar hydrogen generator

An apparatus, using solar energy to manufacture hydrogen by dissociating water molecules into hydrogen and oxygen molecules is described. Solar energy is concentrated on a globe containing water thereby heating the water to its dissociation temperature. The globe is pervious to hydrogen molecules permitting them to pass through the globe while being essentially impervious to oxygen molecules. The hydrogen molecules are collected after passing through the globe and the oxygen molecules are removed from the globe.

Sebacher, D. I.↗
DOE OSTI2025

Levelized cost and carbon intensity of solar hydrogen production via water splitting using a scalable and intrinsically safe photocatalytic Z-scheme raceway system

Generating hydrogen from local energy resources such as solar or wind would unlock a low-carbon energy carrier that could be used to reduce greenhouse gas emissions in sectors such as industry and transportation. Yet, the allocation of new or existing power generation solely to hydrogen production remains contentious due to disputes regarding emissions accounting. Photocatalytic (PC) hydrogen production technologies offer a unique solution, as hydrogen is produced directly from solar energy and water, without the need for electricity generation. However, cost projections for all photocatalytic designs to date have suggested that they are not cost competitive compared to conventional electrolysis systems manufactured at scale. Herein, we offer the first illustrative benchmark of cost and carbon intensity of hydrogen produced in a type 2 “Z-scheme” photocatalytic reactor design, which employs suspended semiconducting nanoconductor particles organized into two stacked volumes in a raceway design. The “Z-scheme” system utilizes two separate photoabsorber particles, tuned to drive either the hydrogen evolution reaction or the oxygen evolution reaction individually, connected via a reversible, charge transfer redox couple in solution. Furthermore, the results suggest a highly competitive and scalable technology, that justifies further experimental validation and prototyping in the field.

Carbon↗
DOE OSTI2026

Water-Fed, Photovoltaic-Driven Anion-Exchange Membrane Water Electrolysis for Solar Hydrogen Production

Direct coupled photovoltaic (PV)-electrolysis is a promising approach for low-cost hydrogen production, avoiding the need for separate electricity generation. Without solar concentration, the operating current densities of a PV-electrolyzer are small, and low capital costs are needed to reach hydrogen production cost targets (<$2/kg). Anion-exchange membrane (AEM) electrolyzers could be well-suited for this application due to their ability to use platinum group metal (PGM)-free catalysts and operate without supporting electrolytes, but a water-fed PV-AEM system has not yet been demonstrated. In this work, the performance of two AEM electrolyzer designs under pure-water, low-temperature, and diurnal-cycling conditions was evaluated. A simple PV-electrolyzer system design with direct electric coupling to a commercial 84 cm2 Si mini module and passive heating and water flow to the electrolyzer was used for on-sun testing in October 2025. The best-performing PV-AEM system achieved an average solar-to-hydrogen (STH) efficiency of 6.6% and a production rate of 15 mg/kWh/m2 of solar irradiance over 11 days. Minimal electrolyzer corrosion was observed, with no loss in efficiency over the diurnal cycles. While highlighting areas for improved electrolyzer and system design, this work is a proof of concept for distributed hydrogen production using inexpensive and abundant materials.

08 HYDROGEN↗
DOE OSTI2026

Development of Composite Photocatalyst Materials that are Highly Selective for Solar Hydrogen Production and their Evaluation in Z-Scheme Reactor Designs

The key technology gap preventing a vertically stacked dual-bed particle suspension reactor from achieving the DOE MYRD&D ultimate cost target for H 2 production remains the lack of materials in particle form factor that exhibit ≥10% solar-to-H 2 energy conversion (STH) efficiency as a suspension. Therefore, our project goals centered around strategies to increase the STH efficiency by enhancing photophysical properties of perovskite oxide particles including increased visible-light absorption, increased selectivity for electrocatalysis of the H 2 evolution reaction (HER) and the O 2 evolution reaction (OER) through development of ultrathin oxide coatings, correlating composition and structure to function, and improving understanding of multiscale transport and kinetic processes.

08 HYDROGEN↗
DOE OSTI2024

Stabilization of Catalytically Active Surface Defects on Ga-doped La–Sr–Mn Perovskites for Improved Solar Thermochemical Generation of Hydrogen

Solar thermochemical hydrogen (STCH) production from water splitting typically requires performing redox cycles at temperatures above 1200 °C to reduce and re-oxidize the bulk of a reversible material. Bulk processes such as oxygen vacancy formation and oxygen diffusion energies dictate the viability of a material for STCH. The surface plays an important role in the formation and destruction of vacancies and interacts with gas phase water and surface adsorbed species. These surface processes can lead to surface reconfigurations and even the formation of surface phases with stoichiometry and oxygen content very different from the bulk composition. Understanding in-situ the surface chemical state and its evolution under water splitting is important to design nonstoichiometric oxides capable of longer-lasting STCH generation at lower temperatures. In this work, we describe the water splitting active defect sites in LSM ((La 0.65 Sr 0.35 ) 0.95 MnO 3–δ ) and Ga-doped LSM ((La 0.6 Sr 0.4 ) 0.95 (Mn 0.8 Ga 0.2 )O 3–δ ) perovskites during Operando thermochemical water splitting conditions using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS) experiments at 800 °C under steam. We show that sub-stoichiometric La +3 in the oxygen-vacancy rich surface at operating conditions can be used to correlate surface water splitting activity and the creation of surface hydroxide intermediates. The addition of Ga in LSM is shown to drastically stabilize the surface chemical composition by preventing Sr segregation and stabilizing catalytically active surface defects that promote the binding of adsorbed hydroxides. Here, we use Operando AP-XPS quantification of metastable surface hydroxide intermediates (La(OH) 3 ) to determine the amount of catalytically active surface sites in LSM (2.9%) and in LSMG (7.8–8.1%, depending on the bulk oxidation state).

08 HYDROGEN↗
DOE OSTI2025

Assessing the deployment of solar-driven hydrogen from biomass at scale in the U.S.

Solar hydrogen from biomass gasification is a promising technology to sustainably produce hydrogen, responsibly dispose biomass waste, and reduce reliance on fossil fuels. However, its large-scale deployment faces challenges due to the geospatial misalignment between biomass resources and solar intensity, which introduces additional supply chain logistics costs. We analyze the logistics cost burden imposed by this misalignment and its impact on successful large-scale deployment of solar-driven hydrogen from biomass in the United States. We also consider associated carbon emissions and explore how the mix of deployed technologies evolves under externally imposed carbon penalties. Our findings show that while economies of scale are known to apply at the processing facility level, the reverse effect occurs at the broader systems-level, driven by logistics. Also, at current technology costs, high carbon penalties would be required to favor deployment of solar based technologies over conventional and hybrid alternatives. We further illustrate strategies and system-level changes to reduce logistics costs and enable sustainable, low-cost hydrogen for decarbonizing different industrial sectors.

Iloeje, Chukwunwike O. [Argonne National Laborator↗