Artificial photosynthesis exists, but only in laboratories and pilot projects. As of October 2026 we found no commercial plant anywhere making fuel this way. The largest outdoor test, a 100 m² array in Japan, peaked at 0.76% solar-to-hydrogen efficiency in 2021, and its own researchers described it as energy negative overall. Lab devices have done far better, but they rely on costly materials and, often, concentrated light.
This article sets out what has actually been built, what the efficiency figures show and why the technology is still waiting for its breakthrough. If you are looking for something that can heat your home or fuel your car today, this is not it. If you want to know how close scientists are to copying a leaf, read on.
What is artificial photosynthesis?
The term covers devices that use sunlight to drive chemistry directly. Ordinary solar panels make electricity; these systems make fuel. The two main products are hydrogen, from splitting water, and carbon-based fuels such as syngas (a mix of carbon monoxide and hydrogen), made from carbon dioxide and water.
Researchers usually describe three approaches:
- Photocatalysis: particles of a light-absorbing powder in water, often laid out in panels.
- Photoelectrochemical (PEC) cells, often called “artificial leaves”: a light absorber coated with catalysts and immersed in water.
- PV-electrolysis: a separate solar cell powering an electrolyser. This is the benchmark the others are measured against, though strictly it is two technologies wired together rather than artificial photosynthesis.
The key figure for all of them is solar-to-hydrogen (STH) efficiency: the share of the sunlight’s energy that ends up stored as hydrogen.
How efficient is a real leaf?
Plants are the yardstick. According to a 2008 review by Zhu, Long and Ort, the theoretical maximum for turning sunlight into biomass is 4.6% for C3 plants (such as wheat and rice) and about 6% for C4 plants (such as maize), under full sunlight. In practice, after respiration and other losses, realised conversion into new growth is typically 2–4%, and crops over a whole season manage a few per cent at best.
So can we beat nature? In the lab, yes, by a wide margin. At scale and outdoors, not yet: the biggest real-world array so far converted less than 1% of sunlight into hydrogen.
How it works
The idea is to copy the two halves of natural photosynthesis. A light-absorbing material, usually a semiconductor, plays the part of chlorophyll. When it absorbs sunlight, it frees up electrons and leaves behind “holes” (missing electrons). Catalysts on the surface then use these to drive two reactions: water is oxidised to release oxygen on one side, and hydrogen ions are reduced to hydrogen gas on the other.
Devices designed to make carbon fuels go a step further, combining carbon dioxide and water to produce syngas. In either case the product is a fuel that can be stored and used when the sun is not shining, which is the main attraction compared with solar energy delivered as electricity.
The catch is materials. The record-breaking devices use rhodium, platinum, lead-containing perovskites or III-V semiconductors (such as gallium arsenide compounds). Claims that artificial photosynthesis does not rely on finite resources do not stand up.
Real-world examples
MIT’s “artificial leaf” (2011)
One of the best-known early devices came from Daniel Nocera’s team at MIT. It was a silicon wafer coated with a cobalt-based catalyst on one side and a nickel-molybdenum-zinc alloy on the other. Dropped into water in sunlight, it stored 2.5% of the light’s energy as chemical energy without wires, and 4.7% when wired up, according to the team’s 2011 paper in Science.
The 2018 direct record
In 2018 a team publishing in ACS Energy Letters reported a single integrated device using rhodium catalysts that reached 19.3% STH efficiency in acid and 18.5% at neutral pH. That was under simulated sunlight in a laboratory, not on a roof.
Japan’s 100 m² array (2021)
The largest outdoor test so far was run by the University of Tokyo’s Domen group, part of the Japanese ARPChem programme. It used 100 m² of panels coated with an aluminium-doped strontium titanate photocatalyst and ran safely for several months. Peak efficiency was 0.76%. The university’s September 2021 release was frank: hydrogen production was “inefficient and energy negative overall”. Japan’s programme has continued with further field work, but we found no published results from it.
EPFL’s kilowatt-scale reactor (2023)
At EPFL in Switzerland, researchers built a parabolic dish that concentrates sunlight about 1,000 times onto an integrated PEC reactor. In a paper in Nature Energy in April 2023, the team reported more than 2 kW of hydrogen output (measured as chemical energy) at an efficiency above 20%, plus useful heat and oxygen. To put 2 kW in context, that is roughly the power of one kettle element, from a dish many metres across.
SunHydrogen’s pilot plans
The US company SunHydrogen (formerly HyperSolar) has announced pilot plants since at least 2019. In 2025 it said it was working with the University of Texas at Austin on a pilot of sixteen PEC panels, each 1.92 m², aimed for late 2025. These are the company’s plans; we could not confirm whether the pilot began operating or what it produced.
What the numbers say
Efficiency records
The highest efficiencies come not from artificial leaves but from PV-electrolysis. In 2016 a Stanford team used a triple-junction solar cell under concentrated light to drive two electrolysers, averaging 30% STH over 48 hours. A 2026 paper from Fraunhofer reports just over 31%.
Set side by side, the gap between lab and field is stark:
| Device | Year | Solar-to-hydrogen efficiency | Conditions |
|---|---|---|---|
| PV-electrolysis (Stanford) | 2016 | 30% (48-hour average) | Concentrated light, lab |
| Integrated PEC device | 2018 | 19.3% | Simulated sunlight, lab |
| EPFL concentrator reactor | 2023 | Above 20% | Outdoor dish, ~1,000× concentration |
| MIT artificial leaf (wireless) | 2011 | 2.5% | Lab |
| Japanese photocatalyst array | 2021 | 0.76% peak | 100 m² outdoors |
| Crop plants (theoretical maximum) | – | 4.6–6% | Full sunlight |
Cost and materials
The record devices use expensive III-V semiconductors and concentrated sunlight; they are nothing like cheap silicon panels. The cheaper, simpler photocatalyst panels tested in Japan are the kind of design that could one day be spread over large areas, but at 0.76% they sit well below what a crop could achieve in theory.
Public money is still going mainly into basic research. In the US, the Department of Energy’s “Fuels from Sunlight” programme in 2020 funded two research hubs, including the Caltech-led LiSA, which received about $60 million over five years.
Limitations
The University of Tokyo team named the main hurdles in 2021: cost, the stability of catalysts and light absorbers, gas separation, and keeping efficiency up at scale.
Stability matters because a fuel plant needs to run for years, while the largest outdoor test so far lasted months. Gas separation is a practical headache: the hydrogen and oxygen come off together and have to be kept apart, which a sheet of powder in water does not do on its own.
The bigger problem is competition. Today the cheapest way to make “solar hydrogen” is ordinary solar panels wired to an electrolyser. Integrated artificial leaves have to beat that combination on cost, not just match nature on efficiency, and none has yet done so. Talk of a “hydrogen revolution” driven by artificial photosynthesis is, for now, ahead of the evidence. The field shares a goal with biomimicry in energy more broadly: nature supplies the idea, but engineering and economics decide whether it scales.
The UK angle
The UK’s best-known work is at the University of Cambridge, in Erwin Reisner’s group. In 2019 the group showed an artificial leaf that made syngas, using a perovskite light absorber on glass. In 2022 it published lightweight floating “leaves” made of perovskite and bismuth vanadate on plastic film, ranging from 1.7 cm² up to 100 cm², which made syngas from water and carbon dioxide. That work was co-funded by the Austrian government and the energy company OMV through a Christian Doppler Laboratory. Reisner said at the time that the devices were not yet commercially viable and that the aim was to scale up from square centimetres to square metres.
The UK also has a Solar Fuels Network, an EPSRC-supported research community, and Newcastle hosted the 5th International Solar Fuels Conference on 1–5 September 2025, with the Royal Society of Chemistry. We found no UK company selling fuel made by artificial photosynthesis in 2026. For British homes, the established ways to use sunshine remain solar panels for electricity and, for those exploring other plant-based energy, biomass energy, which uses natural photosynthesis directly.
Frequently asked questions
What is artificial photosynthesis?
It is the use of sunlight to drive chemical reactions that make fuel, usually hydrogen from water, or syngas from water and carbon dioxide. It copies the principle of plant photosynthesis but produces a storable fuel instead of plant material.
Does artificial photosynthesis exist yet?
Yes, but only in labs and pilot projects. As of October 2026 there are no commercial artificial-photosynthesis fuel plants. The largest outdoor test, in Japan, peaked at 0.76% efficiency in 2021 and was energy negative overall.
Is an artificial leaf more efficient than a real one?
In the lab, the best integrated device reached 19.3% in 2018, well above a plant’s theoretical maximum of 4.6–6%. But that used rhodium catalysts and simulated sunlight. The large, cheap outdoor array in Japan managed 0.76%, below what crops typically achieve.
What is the difference between an artificial leaf and PV-electrolysis?
An artificial leaf is a single device that absorbs light and splits water in one place. PV-electrolysis uses a solar cell to make electricity, which then powers a separate electrolyser. PV-electrolysis holds the efficiency records (30% in 2016, just over 31% in a 2026 paper) and is currently the cheaper route to solar hydrogen.
Does artificial photosynthesis rely on rare materials?
The record devices do. They use rhodium, platinum, lead-containing perovskites or III-V semiconductors, which makes them expensive and harder to scale than silicon solar panels.
Can artificial photosynthesis power my home?
No, not today. Nothing is on sale for homes. If you want to use sunshine at home, conventional solar panels are the established option; check current scheme rules on GOV.UK or with an MCS-certified installer.