Planar perovskite solar cells using low‐temperature atomic layer deposition (ALD) of the SnO2 electron transporting layer (ETL), with excellent electron extraction and hole‐blocking ability, offer significant advantages compared with high‐temperature deposition methods. The optical, chemical, and electrical properties of the ALD SnO2 layer and its influence on the device performance are investigated. It is found that surface passivation of SnO2 is essential to reduce charge recombination at the perovskite and ETL interface and show that the fabricated planar perovskite solar cells exhibit high reproducibility, stability, and power conversion efficiency of 20%.

Reversible hydrogen sorption coupled with the MgH2↔Mg phase transformation was achieved in the remarkably low 340 -425 K temperature range using MgH2-TiH2 composite nanoparticles obtained by reactive gas-phase condensation of Mg-Ti vapours under He/H2 atmosphere. The equilibrium pressures determined by in situ measurements at low temperature were slightly above those predicted using enthalpy H and entropy S of bulk magnesium. A single van 't Hoff fit over a range extended up to 550 K yields the thermodynamic parameters H = 68.1±0.9 kJ/molH2 and S = 119±2 J/K•molH2 for hydride decomposition. A desorption rate of 0.18 wt% H2/min was measured at T=423 K and p(H2)≈ 1 mbar, i.e. close to equilibrium, without using a Pd catalysts. The nanoparticles displayed a small absorption-desorption pressure hysteresis even at low temperatures. We critically discuss the influence exerted by nanostructural features such as interface free energy, elastic clamping, and phase mixing at the single nanoparticle level on equilibrium and kinetic properties of hydrogen sorption.

CO 2 hydrogenation over catalysts is a potentially exciting method to produce fuels while closing the CO 2 cycle and mitigating global warming. The mechanism of this process has been controversial due to the difficulty in clearly identifying the species present and distinguishing which are reaction intermediates and which are byproducts. We in situ manipulated the independent formation and hydrogenation of each adsorption species produced in CO 2 hydrogenation reaction over Ru/Al 2 O 3 using operando diffuse reflectance infrared Fourier transformation spectroscopy (DRIFTS) and executed a novel iterative Gaussian fitting procedure. The adsorption species and their role in the CO 2 hydrogenation reaction have been clearly identified. The adsorbed carbon monoxide (CO*) of four reactive structures was the key intermediate of methane (CH 4) production. Bicarbonate (HCO 3 − *), formed on the metal−support interface, appeared to be not only the primary product of CO 2 chemisorption but also a reservoir of CO* and consisted of the dominate reaction steps of CO 2 methanation from the interface to the metal surface. Bidentate formate (Bi-HCOO − *) formed on Ru under a certain condition, consecutively converting to CO* to merge into the subsequent methanation process. Nonreactive byproducts of the reaction were also identified. The evolution of the surface species revealed the essential steps of the CO 2 activation and hydrogenation reactions which were inevitably initiated from HCO 3 − * to CO* and finally from CO* to CH 4 .

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