Oxygen evolution reaction (OER) is the core process - but also the bottleneck - in many energy devices such as metal-air batteries and water-splitting techniques, calling for new insights in rational design of OER electrocatalysts. The perovskite family exhibits superb OER reactivity, but its poor conductivity remains a big problem, not to mention that the morphology of perovskite oxides is hard to control. In situ hybridization of perovskite oxides with conductive frameworks is an efficient strategy to solve these problems, as researchers report in new work.
Solar cells absorb incoming sunlight and convert a part of photon energy into electricity. The remainder of photon energy is dissipated as heat. Although the idea is rather counter-intuitive, 'reverse solar cell' systems can also generate electric power by emitting rather than absorbing photons. Such systems - known as thermoradiative cells - generate voltage and electric power via non-equilibrium thermal radiation of infrared photons. Thermoradiative cells offer an opportunity to generate clean energy by harvesting radiation from largely untapped terrestrial thermal emission sources, potentially including the Earth itself.
Researchers have explored the role of intrinsic bulk electrical conductivity and surface polarity in the electrocatalysis of polysulfide redox reactions. They synthesized highly porous and conductive titanium carbide (TiC)-based composite cathode materials and to assemble lithium-sulfur (Li-S) batteries with high sulfur loading. Li-S cells employing the as-synthesized TiC-based cathode exhibited reduced internal resistance, enhanced energy efficiency, and prolonged service life.
Traditionally, the size of electrode materials in supercapacitors is reduced to nanometers to enable high surface area and more room for storing more amounts of energy. But the microscopic electron distribution in nanocarbons limits the total amount of stored energy through a property called 'quantum capacitance'.
Although a lot of charge could be stored in the pores on nanocarbons due to their high surface area, their inherently low quantum capacitance reduces the net energy that could be drawn from supercapacitors. Researchers have controllably added nitrogen atoms to graphene to achieve carbon supercapacitors ready for practical applications.
The fact that temperature differentials (heat) are ubiquitously present in our environment makes thermoelectric energy harvesting a highly attractive research field. New work highlights the fabrication of flexible thermoelectric materials and modules by merging colloidal nanomaterials (quantum dots) that can be tuned for efficient heat-to-electricity energy conversion with naturally abundant cellulose paper that are low in cost and have inherently low thermal conductivity.
Sodium-ion batteries (SIBs) represent an attractive alternative to lithium-ion batteries, owing to the fact that sodium resources are practically inexhaustible and evenly distributed around the world while the ion insertion chemistry is largely identical to that of lithium. Researchers have now rationally designed and fabricated a sodium ion full battery where both of the cathode and anode materials possessed very unique two-dimensional nanostructured architecture. The 2D nanostructured architecture results in excellent rate capability and stable cycling performance.
Although developed only recently, inorganic halide perovskite quantum dot systems have exhibited comparable and even better performances than traditional quantum dots in many fields. They are expected to be applied in display and lighting technologies. Researchers now have reported an interesting cyclable surface dissolution and recrystallization phenomenon of inorganic perovskite crystals. This allows them to freely change size between nanometer and micrometer scales, and can be used to healing the defects inside perovskite films and hence improve the performances of optoelectronic devices.
Self-powered nanotechnology based on these nanogenerators aims at powering nanodevices and nanosystems using the energy harvested from the environment in which these systems are suppose to operate. An interesting approach comes from a group of Chinese scientists who propose to scavenge the large amounts of wasted wind energy in cities: they propose hybridized nanogenerator that consists of a solar cell and a triboelectric nanogenerator, which can be utilized to individually or simultaneously scavenge solar and wind energies.