Power/Performance Bits: Jan. 21

New research out of Cambridge is said to provide evidence that superconductors could be used as an energy-efficient source for spintronic devices. Meanwhile, by replacing platinum with molybdenum in photoelectrochemical cells, scientists from Ecole Polytechnique Fédérale de Lausanne in Switzerland have developed a cheaper and scalable technique that can greatly improve hydrogen production through water splitting as a means of storing solar energy.

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Spinning towards superconduction
With spintronics widely believed to be the basis of a future revolution in computing, researchers at the University of Cambridge are reporting what they said is the first evidence that superconductors could be used as an energy-efficient source for so-called “spin-based” devices, which are already starting to appear in electronic devices.

Spintronic devices exploit a fundamental property of an electron, called “spin,” unlike conventional electronic devices, which transmit information via the charge carried by an electron. Simply, ‘spin’ refers to the intrinsic angular momentum of the electron, and makes it behave like a tiny magnet. Spintronics involves manipulating this to perform logic operations in devices, the researchers reminded.

But there is a catch in that any such device requires a large spin current to operate, which in itself requires the input of a large electrical charge. Since the spin currents are dissipative, a large fraction of the input energy is wasted as heat. However, superconductors – materials which when cooled below a certain temperature, can carry a current without losing energy – provide one potential solution to this. If these materials could be harnessed in spin-based devices, an energy-efficient source for the charge required to create spin currents could be provided.

The Cambridge research shows for the first time, that the natural spin of electrons can be manipulated, and more importantly detected, within the current flowing from a superconductor, which could pave the way for the use of superconductors in spintronics, making these devices more energy-efficient.

High-performance computers such as those used in large-scale data handling facilities such as e-data centers waste huge amounts of energy. In Europe, about 3 percent of the energy generated is consumed by them. The researchers suggest that if spintronics could be combined with superconductivity, the benefits of both could be taken advantage of to reduce this. Circuits could be created that are highly complex and extremely powerful on the one hand, but very low in terms of their energy demands on the other.

Storing solar energy on the cheap
While many believe solar energy appears to be the only form of renewable energy that can be exploited at level that matches the world’s growing needs, it is equally necessary to find efficient ways to store solar energy in order to ensure a consistent energy supply when sunlight is scarce. One of the most efficient ways to achieve this is to use solar energy to split water into hydrogen and oxygen, and get the energy back by consuming hydrogen in a fuel cell, according to researchers at Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland that have found a method to create a high-efficiency, scalable solar water splitting device using cheap materials.

One of the most sustainable methods of producing hydrogen is photoelectrochemical water-splitting. Solar energy is used to break water molecules into hydrogen and oxygen through a process called “hydrogen evolution reaction,” which requires a catalyst. In photoelectrochemical water-splitting devices, a common catalyst used to split water is platinum.

Researchers at EPFL found a way to make efficient solar-powered water splitting devices using abundant and cheap materials. A molybdenum-sulfide catalyst was created for the hydrogen evolution reaction, along with copper(I) oxide as a photocathode. The researchers found that the molybdenum sulfide can be deposited on the copper(I) oxide photocathode for use in photoelectrochemical water splitting through a simple deposition process that can be easily expanded onto a large scale.

The technique shows comparable efficiency to other hydrogen evolution reaction catalysts like platinum, it preserves the optical transparency for the light-harvesting surface and it shows improved stability under acidic conditions, which could translate into lower maintenance.

More importantly, both the catalyst and the photocathode are made with cheap, earth-abundant materials that could greatly reduce the cost of photoelectrochemical water-splitting devices in the future.