Solar-to-hydrogen conversion improved

Posted Mar 3, 2018 by Tim Sandle
A new study shows how nanostructuring can increase the efficiency of metal-free photocatalysts by factor 11. This development is important for solar-to-hydrogen conversion and boosting energy efficiency.
The Tri-Gen plant will produce enough hydrogen to power about 1 500 vehicles on an average daily use...
The Tri-Gen plant will produce enough hydrogen to power about 1,500 vehicles on an average daily use cycle.
© Toyota Motor Sales, U.S.A., Inc.
The research comes from the Berlin based research institute, the Helmholtz-Zentrum Berlin für Materialien und Energie (HZB). The study shows that polymeric carbon nitrides can exhibit a catalytic effect in sunlight. This phenomenon can then be exploited to boost the efficiency of the production of hydrogen from solar energy. Given that the efficiency of these metal-free catalysts is relatively low, the catalytic efficiency of these polymeric carbon nitrides can be increased by up to a factor 11 through re-configuring the set-up in order to create a larger surface area.
Interest in renewable energy continues to grow and solar energy is one of the most popular and promising. However, a considerable challenge arises with the need to supply energy when the sun is not shining. Here hydrogen production, by splitting water with the help of sunlight, provides an potential solution.
Hydrogen is an efficient energy storage medium. For the production process catalysts are required to split the water. One of the most efficient is platinum, but the downside is with the cost of the metal. This has led to several research centers seeking wlower-cost alternatives catalysts.
Dr. Tristan Petit, from HZB, is pioneering studies with metal-free photocatalysts. Photocatalysis is the acceleration of a photoreaction in the presence of a catalyst. In the process of catalysed photolysis, light is absorbed by an adsorbed substrate. The most promising type are polymeric carbon nitrides.
To boost the efficiency of this type of catalyst, the researchers have expanded the surface area. They have achieved this through a novel two-step heat treatment method, which separates out the individual sheets of carbon nitride from each other. The output is sheets of large pores containing different amino groups with specific functionalities, which substantially increase the energy conversion efficiency.
The new study has been published in the journal Energy & Environmental Science. The research paper is titled "Engineering oxygen-containing and amino groups into two-dimensional atomically-thin porous polymeric carbon nitrogen for enhanced photocatalytic hydrogen production."