A group of scientists has figured out a new way to efficiently produce hydrogen using solar energy. The device uses solar energy to separate water into hydrogen and oxygen or it can use carbon dioxide to form carbon monoxide and oxygen. It works by directing sunlight through a quartz window to a reaction chamber where most of the photons are captured and converted to heat. The extreme heat created then causes the catalyst, a cylinder of porous cerium dioxide, to lose one of its oxygen atoms. Once this chemical reaction tapers off, determined by the flow of released oxygen, the temperature is dropped and the reactant added. If water vapor is added, the catalyst uses the oxygen in the water to recreate cerium dioxide and hydrogen is released. If carbon dioxide is added, one oxygen is taken by the catalyst and carbon monoxide is released.
A complex formula was used by the authors to calculate efficiency and the results were quite remarkable. According to the authors:
Performance of the device created by the group stabilized after the first 100 cycles and remained so for up to 400 cycles. Aside from the impressive efficiency, adding to the appeal is that the hardware was designed for bulk manufacturing. However, as efficient as the device is, it is not perfect. Only pure reactants must be used to avoid build up of contaminants on the catalyst, and purifying water is an energy intensive process.The solar-to-fuel energy conversion efficiency obtained in this work for CO2 dissociation is about two orders of magnitude greater than that observed with state-of-the-art photocatalytic approaches. The gravimetric hydrogen production rate exceeds that of other solar-driven thermochemical processes by more than an order of magnitude.
[Source: Wired | Image: Tom Raftery – C.C. License 2.0]