Clean Energy Breakthrough: Scientists Improve Light-Driven Water-Splitting to Produce Hydrogen

Light-Driven Hydrogen Production

A step closer to an efficient way of producing hydrogen so that we can finally do without fossil fuels and other energy sources that are harmful to our planet. Credit: Tokyo University of Science

Etching the Road to a Hydrogen Economy Using Plasma Jets

Hydrogen is a clean energy source that can be produced by splitting water molecules with light. However, it is currently impossible to achieve this on a large scale. In a recent breakthrough, scientists at Tokyo University of Science, Japan, developed a novel method that uses plasma discharge in solution to improve the performance of the photocatalyst in the water-splitting reaction. This opens doors to exploring a number of photocatalysts that can help scale-up this reaction.

The ever-worsening global environmental crisis, coupled with the depletion of fossil fuels, has motivated scientists to look for clean energy sources. Hydrogen (H2) can serve as an eco-friendly fuel, and hydrogen generation has become a hot research topic. While no one has yet found an energy-efficient and affordable way to produce hydrogen on a large scale, progress in this field is steady and various techniques have been proposed.

One such technique involves using light and catalysts (materials that speed up reactions) to split water (H2O) into hydrogen and oxygen. The catalysts have crystalline structures and the ability to separate charges at the interfaces between some of their sides. When light hits the crystal at certain angles, the energy from the light is absorbed into the crystal, causing certain electrons to become free from their original orbits around atoms in the material. As an electron leaves its original place in the crystal, a positively charged vacancy, known as a hole, is created in the structure. Generally, these “excited” states do not last long, and free electrons and holes eventually recombine.

This is the case with bismuth vanadate (BiVO4) crystal catalysts as well. BiVO4 has been recently explored for water-splitting reactions, given its promise as a material in which charge-separation can occur upon excitation with visible light. The quick recombination of pairs of charged entities (“carriers”) is a disadvantage because carriers must separately partake in reactions that break up water.

In a recent study published in Chemical Engineering Journal, scientists from the Photocatalysis International Research Center at Tokyo University of Science, Japan, together with scientists from Northeast Normal University in China, developed a novel method to improve the charge-separation characteristics of decahedral (ten-sided) BiVO4 crystal catalysts. Prof Terashima, lead scientist in the study, explains, “Recent studies have shown that carriers can be generated and separated at the interfaces between the different faces of certain crystals. In the case of BiVO4, however, the forces that separate carriers are too weak for electron-hole pairs that are generated slightly away from the interfaces. Therefore, carrier separation in BiVO4 decahedrons called for further improvements, which motivated us to carry out this study.”

In the technique they propose, BiVO4 nanocrystals are exposed to what is called “solution plasma discharge”, a highly charged jet of energetic matter that is produced by applying high voltages between two terminals submerged in water. The plasma discharge removes some vanadium (V) atoms from the surface of specific faces of the crystals, leaving vanadium vacancies. These vacancies act as “electron traps” that facilitate the increased separation of carriers. Because these vacancies are in greater number on the eight side faces of the decahedron, electrons are trapped on these faces while holes accumulate on the top and bottom faces. This increased charge separation results in better catalytic performance of the BiVO4 nanocrystals, thereby improving its water splitting performance.

This study represents a novel use of solution plasma discharge to enhance the properties of crystals. Prof Akira Fujishima, co-author of the paper, says, “Our work has inspired us to reconsider other crystals that are apparently ineffective for water splitting. It provides a promising strategy using solution plasma to ‘activate’ them.” The use of solution-plasma discharge has many advantages over using conventional gaseous plasma that make it far more attractive from both technical and economic standpoints. Prof Xintong Zhang from Northeast Normal University, China, remarks, “Unlike gaseous plasma, which has to be generated in closed chambers, solution plasma can be generated in an open reactor at room temperature and in a normal air atmosphere. In addition, by working with crystal powders in a solution, it becomes more convenient to change the parameters of the process, and it is also easier to scale up.”

This study hopefully takes us one step closer to an efficient way of producing hydrogen so that we can finally do without fossil fuels and other energy sources that are harmful to our planet. Further commenting on the promise of this study, Prof Terashima says, “If efficient hydrogen energy can be produced using sunlight and water, two of the most abundant resources on earth, a dream clean society could be realized.”

Reference: “Solution plasma boosts facet-dependent photoactivity of decahedral BiVO4” by Guangshun Che, Dandan Wang, Changhua Wang, Fei Yu, Dashuai Li, Norihiro Suzuki, Chiaki Terashima Akira Fujishima, Yichun Liu and Xintong Zhang, 15 May 2020, Chemical Engineering Journal.
DOI: 10.1016/j.cej.2020.125381

3 Comments on "Clean Energy Breakthrough: Scientists Improve Light-Driven Water-Splitting to Produce Hydrogen"

  1. The easiest way to slow or stop global warming is to figure out ways that we can live without the need for so much use of energy! We have to design houses and dwellings that don’t need air-conditioning or much heating from fossil fuel or electric. It’s possible. If we made dwellings where the walls and ceilings are always a certain temperature then for sure all the molecules, air, in the room will certainly stay at that temperature. It works! I do it all the time wherever I live. I cool the walls at night with the cool night air blowing into my dwelling from a fan I put in the window(s). If you make your dwellings walls cold at night with forced air from fans cooling the walls and then when the cool air at night starts warming up in the mourning from the sun, which is usually an hour after sunrise, you then take the fans out of the windows and close the windows. This will keep the cool air in the room. If the cool air molecules in the room has the cool walls to help all the cool air molecules cool then that cool air will stay cooler than it would in a dwelling that didn’t do that. We have to design gadgets that will suck the outside air into something that will cool the air in a way that doesn’t use air-conditioning. We should make a device that takes the outside air and runs that air through a chamber that has multiple coils or panels filled with the water from the water lines that dwellings have that are used for toilet water. These cooled water filled coils or panels are then sealed up when the sun rises thus retaining their coolness better. During the day we then circulate the air in the room through a maze that has all the cooled water coils or panels. As the air in the room hits those coils or panels it will surely cool down. This action could help keep a dwelling cooler throughout the day. Then we have to make it so that dwellings that already exist can easily put these gadgets into their dwellings through the window or we make it so it can be attached to the dwelling in the inside or out side through a small hole in the wall. We can also make gadgets that would use the sun to heat things that would then be used to provide heat to a dwelling. We could also make a tarp like material that would be layered in sections over dwellings so to keep the sun rays off the dwelling during warm times. This and all these suggestions would immediately would save an enormous amount of energy NOW and do it without any high tech inventions. I try to tell you how to stop global warming in many other ways on my Facebook Page that could be done right now. I don’t have much longer to live so hopefully someone will get these ideas I discuss started and save our planet from the very soon, in about twenty years, epict weather change that the Earth will experience once the permafrost is melted in the Arctic region of the planet and most or all the snow and ice is melted from the North and South Poles and all the ice and snow has melted on mountain tops around the world. All of this will SURELY happen in about 20 years because right now and ever since the 1960’s the permafrost in Russia’s part of the planet has been melting on a massive scale. There are pictures on the internet that shows how the melted water from the melted permafrost has been flowing into the ocean off of Russia where it has been warming up the North Pole’s water as it swirls throughout the waters of the Arctic region. You can see on these photos how over the years the water from Russia’s melting permafrost and now Greenland’s melting permafrost will surely succeed in warming up the Earth’s oceans enough to cause much more havoc on our environment than we are experiencing today. In about 20 years the Earth climate will change! You got 20 years to figure out a way to survive because the Earth won’t be the same any more. The Earth will in 20 years be on a path to destruction beyond our control. Massive droughts, massive starvation and massive deaths from diseases, massive unrest will engulf the world. YOU ALL better do something to slow the for sure upcoming global change that will happen in about twenty years. These inventions you seek to save our planet will still be on the drawing boards or under construction in twenty years! WE NEED something done NOW! Design our lives now so that we don’t use polluting energy or our days of agony will be here sooner than we like! Once the Earth gets to a certain point there is no turning back the destruction that the Sun can do to a planet. The Sun cooked Venus, Mars and Suns cook planets throughout the solar system. We had a good thing going here on Earth. A one of a kind planet. Well, that one of a kind planet can no longer exist because of the behavior of it’s inhabitants the humans. PLEASE someone make these and many other gadgets I’m trying to get you to make to save this planet. I hate for my granddaughter as well as all of you to have to deal with problems that we could solve today. If we can stop the many ways we are warming up the Earth now then perhaps the permafrost won’t melt which would mean a lot less warmer water going into the oceans which means colder ocean water which means less global warming! Then if we do this we will enable the Earth to make more snow and ice which will be needed! The choice is yours! Either save your planet now or kiss your butts goodbye!

  2. Hydrogen can be clean energy storage but it’s use as fuel in vehicles or small residential/industrial units to generate electric power through fuel cells will be very harmful for nature. Water vapour exhaust of Hydrogen Fuel Cells, has great property of GHG emissions enforcing global warming more than fossils fuel use. Water vapour exhaust in atmosphere condenses at height creating water droplets which have property to absorb light energy from sun to heat up atmosphere and stop heat energy escaping Earth ground. Increase of water droplets result precipitation which may occur irregularity depending on intensity of water vapour out causing abnormal effect on seasonal agricultural production. Further high water droplets form cloud in atmosphere restricting sunlight entry at Earth. This will decrease solar energy production as clean energy. Solar energy can be used to meet all world power demand using hydrogen as energy storage and Fuel Cells to backup. But cloud may affect solar energy as well as saving of energy in form of Hydrogen. Fossil Fuels may be used to generate Hydrogen as energy storage at high energy expenditure.
    Water vapour from hydrogen fuel cells shall be more dangerous as GHG emissions than fossil fuels GHG emissions. Being clean energy production, renewable, high energy storage and clean water & heat exhaust from fuel Cells likely to increase Global warming, climate change, impact on agricultural production, forcing to use limited fossil fuels on earth instead of solar energy. Hydrogen as energy storage may be more harmful to nature and life on Earth may be under high threat. Present setup of using hydrogen as energy source may give more negative result than its non use.
    Can Hydrogen be made useful eco-friendly renewable energy source? Yes.
    Modular power plants consisting solar panels, energy storage as Hydrogen and backup from fuel Cells to feed Grids and overhead supply line for powering EVs on roads. Modular plant will restrict water vapour in one unit and feed can electric energy for moving vehicles, residentia & industrial use world wide.
    This will be effective with use of New technology of EVs powered by overhead supply line driving freely like fuel vehicle being receiving power from overhead without short circuit. This technology is marked as an INVENTION by experts. By using new technology, solar energy with hydrogen as energy storage will be ultimate energy source for whole world without affecting Climate or any natural activities.

  3. Woooow amazing★★★

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