Solar–to-hydrogen conversion

Polymeric carbon nitrides exhibit a catalytic effect in sunlight that can be used for the production of hydrogen from solar energy.

However, the efficiency of these metal-free catalysts is extremely low. A team at the Tianjin University in China, in collaboration with a group at the Helmholtz-Zentrum Berlin, has increased the catalytic efficiency of these polymeric carbon nitrides by a factor eleven through a simple process resulting in a larger surface area. The paper was published in the journal Energy & Environmental Science.

One of the major challenges of the energy transition is to supply energy even when the sun is not shining. Hydrogen production by splitting water with the help of sunlight could offer a solution. Hydrogen is a good energy storage medium and can be used in many ways. However, water does not simply split by itself. Catalysts are needed, for instance Platinum, which is rare and expensive. Research teams the world over are looking for more economical alternatives. Now a team headed by Dr. Tristan Petit from the HZB, together with colleagues led by Prof. Bin Zhang from Tianjin University, Tianjin, China, has made important progress using a well-known class of metal-free photocatalysts.

>Read more on Bessy II at HZB website

Image: PCN nanolayers under sunlight can split water.
Credit: Nannan Meng /Tianjin University

Scientists confirm speculation on the chemistry of a high-performance battery

X-ray experiments at Berkeley Lab reveal what’s at work in an unconventional electrode.

Scientists have discovered a novel chemical state of the element manganese. This chemical state, first proposed about 90 years ago, enables a high-performance, low-cost sodium-ion battery that could quickly and efficiently store and distribute energy produced by solar panels and wind turbines across the electrical grid.

This direct proof of a previously unconfirmed charge state in a manganese-containing battery component could inspire new avenues of exploration for battery innovations.

X-ray experiments at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) were key in the discovery. The study results were published Feb. 28 in the journal Nature Communications.

Scientists at Berkeley Lab and New York University participated in the study, which was led by researchers at Natron Energy, formerly Alveo Energy, a Santa Clara, California-based battery technology company.

The battery that Natron Energy supplied for the study features an unconventional design for an anode, which is one of its two electrodes. Compared with the relatively mature designs of anodes used in lithium-ion batteries, anodes for sodium-ion batteries remain an active focus of R&D.

>Read more on the Advanced Light Source website

Photo: An array of solar panels and windmills.
Credit: PxHere

Fuel from the sun: insight into electrode performance

Soft x-ray studies of hematite electrodes—potentially key components in producing fuel from sunlight—revealed the material’s electronic band positions under realistic operating conditions.

In photosynthesis, plants use sunlight to split water into oxygen and hydrogen. The oxygen is released into the atmosphere, and the hydrogen is used to produce molecules—such as carbohydrates and sugars—that store energy in chemical bonds. Such compounds constitute the original feedstocks for subsequent forms of fuel consumed by society.

Photoelectrochemical (PEC) water splitting is a form of “artificial” photosynthesis that uses semiconductor material, rather than organic plant material, to facilitate water splitting. Electrodes made of semiconductor material are immersed in an electrolyte, with sunlight driving the water-splitting process. The performance of such PEC devices is largely determined at the interface between the photoanode (the electrode at which light gets absorbed) and the electrolyte.

>Read more on the ALS webpage

Photo: Roy Kaltschmidt