Insights from nature for more efficient water splitting

June 30, 2014

Water splitting is one of the critical reactions that sustain life on earth, and could be a key to the creation of future fuels. It is a key in the process of photosynthesis, through which plants produce glucose and oxygen from water and carbon dioxide, using sunlight as energy. However, there are still significant mysteries about the process. Nature's own water-splitting catalysts?which are based on manganese rather than more common elements such as iron, copper, or nickel?are incredibly efficient, and scientists have long been studying why this is so and how we can mimic the natural system.

One basic riddle is why nature always uses manganese, a fact that is particularly surprising considering that manganese is rather inactive at neutral pH, which is how water is found in nature. Scientists have been able to devise many artificial manganese-based catalysts of their own, but have not been able to make them active at neutral pH. Now, in a study published in Nature Communications, a team from the RIKEN Center for Sustainable Resource Center led by Ryuhei Nakamura has reported the discovery of a mineral-based catalyst that can efficiently split water into oxygen and hydrogen ions (protons) at neutral pH.

They key to this work, according to Nakamura, was the insight, based on spectrographic findings, that the catalysis of water splitting can only be efficient if the transfer of electrons and protons is properly synchronized. Normally, artificial catalysts do not do this. With this in mind, the team devised a new strategy for remedying this mismatch of electron- and proton-transfer timing, and through it were able to achieve a significant improvement in the catalytic activity of manganese oxides at neutral pH.

Learning from nature is an important theme of this research. According to Nakamura, "The alpha-manganese oxide we used in this work is a main component of naturally occurring manganese minerals. We were surprised to discover that even mineral-like manganese oxides can split water efficiently at neutral pH once the timing of the electron and proton transfer is synchronized. This finding inspired us to think about how nature engineered the normally inactive manganese mineral to become an active catalyst for water splitting."

Renewable energy sources such as solar, wind, hydroelectric and geothermal fluctuate over time, and storing this energy is a crucial task for creating a sustainable society. Water splitting can be used to transform energy into hydrogen that can then be combined with oxygen from the atmosphere in clean fuel cells or with carbon dioxide in the oceans or atmosphere to create raw materials for hydrocarbon fuels and materials. Nakamura hopes to use this new knowledge to construct an electrochemical water splitting device that can operate at neutral pH, thus exploiting water as a resource to create new fuels.

For Nakamura, this work has exciting future potential. "As seen from a flower in a vase," he explains, "plants can use even tap water as a resource to make fuels. They do not need acid and base solutions. In other words, nature utilizes a safe, clean, and abundant form of water, thereby creating truly sustainable ecosystems. I hope that our findings will be able to contribute to the use of water at a neutral pH as a resource for generating renewable energy, which is one of the foundations for sustainable human societies."


Related Manganese Articles from Brightsurf:

Stellar explosion in Earth's proximity
When the brightness of the star Betelgeuse dropped dramatically a few months ago, some observers suspected an impending supernova - a stellar explosion that could also cause damage on Earth.

Lightweight green supercapacitors could charge devices in a jiffy
In a new study, researchers at Texas A&M University have described their novel plant-based energy storage device that could charge even electric cars within a few minutes in the near future.

Manganese single-atom catalyst boosts performance of electrochemical CO2 Reduction
A research team led by Prof. ZHANG Suojiang from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences prepared a manganese (Mn) single-atom catalyst (SAC) with Mn-N3 site supported by graphitic C3N4, which exhibited efficient performance of CO2 electroreduction.

Way, shape and form: Synthesis conditions define the nanostructure of manganese dioxide
Scientists at Tokyo Institute of Technology explore a novel and simplistic method to synthesize manganese dioxide with a specific crystalline structure called β-MnO2.

Bacteria with a metal diet discovered in dirty glassware
Newfound bacteria that oxidize manganese help explain the geochemistry of groundwater.

Higher manganese levels in early pregnancy linked to lower preeclampsia risk
An analysis of data from more than 1,300 women followed prospectively through pregnancy found that women with lower levels of the essential mineral manganese in early pregnancy were more likely to develop the serious high blood pressure syndrome called preeclampsia in late pregnancy.

Supercapacitor promises storage, high power and fast charging
A new supercapacitor based on manganese oxide could combine the storage capacity of batteries with the high power and fast charging of other supercapacitors, according to researchers at Penn State and two universities in China.

Topological materials for information technology offer lossless transmission of signals
New experiments with magnetically doped topological insulators at BESSY II have revealed possible ways of lossless signal transmission that involve a surprising self-organisation phenomenon.

Scientists link decline of baltic cod to hypoxia -- and climate change
If you want to know how climate change and hypoxia -- the related loss of oxygen in the world's oceans -- affect fish species such as the economically important Baltic cod, all you have to do is ask the fish.

Secure printing with water-based invisible ink
Researchers in China have developed a rewriteable paper coating that can encrypt secret information with relatively low-tech invisible ink -- water.

Read More: Manganese News and Manganese Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to