Volume 2 Issue 1, January 2017

As renewable energy industries grow, a city in England is trying to understand if cultural tourism can be used to build an energy hub.

Gasoline taxes are considered to be a cost-effective policy instrument for reducing carbon emissions. A study finds that while gasoline taxes rose in 83 countries between 2003 and 2015, the global mean fell by 13.3% due to a shift in consumption towards countries that maintain gasoline subsidies or that have low taxes.

The efficiency of single-junction solar cells is intrinsically limited and high efficiency multi-junctions are not cost effective yet. Now, semi-transparent perovskite solar cells suggest that low cost multi-junctions could be within reach.

Extensive efforts are under way to increase not only the efficiency but also the stability of organic-inorganic halide perovskite based solar cells. However, research shows that iodine-containing perovskites are vulnerable to a self-degradation pathway that may inherently limit their lifetime.

Organolead halide perovskite solar absorbers demonstrate high photovoltaic efficiencies but they are notorious for their intolerance to water. Now, methylammonium lead iodide perovskites are used to harvest solar energy — in water — via photocatalytic generation of hydrogen from solutions of hydriodic acid.

Planar structured perovskite solar cells often show hysteresis and lower efficiency than mesoporous ones. Jiang et al. show that using a SnO₂ electron transport layer improves the performance of planar devices, reporting a certified efficiency of 19.9%, and enables a lower processing temperature.

Organometal halide perovskite materials have been the subject of intensive research efforts in the context of photovoltaic applications. Here the authors exploit dynamic equilibrium to photocatalytically generate hydrogen from aqueous HI solutions using methylammonium lead iodide.

Electrocatalytic water oxidation is key in energy storage technologies, but deeper mechanistic understanding is still required. Grimaud et al. show that surface oxygen atoms in a model oxide catalyst act as electrophilic centres for reactions and observe drastic reconstruction of the catalyst surface.

Perovskite solar cells grown in substrate configuration would open a range of applications, if various challenges could be overcome. Towards that aim, Fu et al. present an architecture allowing inverted semi-transparent planar perovskite solar cells with open-circuit voltage of 1.116 V and 16.1% efficiency.

Using photoelectrodes to split water is a promising approach to convert solar energy to fuel, but photoanode stability is often an issue. Now, a Mo-doped BiVO₄ photoanode is shown to stably evolve oxygen for 1,000 h due to in situ regeneration of the catalyst, and inhibition of photocorrosion.

Extensive efforts are under way to tackle the degradation issue—one of the biggest challenges for the practical application of perovskite-based solar cells. Here the authors show that CH₃NH₃PbI₃ and several other iodine-containing perovskites are inherently unstable due to decomposition caused by self-generated I₂.

Reforms of energy markets are necessary to face the low carbon transition but are problematic to measure. New data evaluate implicit taxes and subsidies for gasoline in almost all countries at monthly intervals showing mixed results that highlight the difficulty in implementing effective policy tools.