We believe that the performance of the prediction models can be enhanced with the use of more patient data. As future work, we plan to directly contact hospitals in Riyadh in order to collect more information related to patients with MERS-CoV infections.

challenging even on the catalyst surface. [4] Thus, although the thermodynamic potentials of nitrogen reduction reaction (NRR) and hydrogen evolution reaction (HER) are similar, the kinetic activity of NRR (such as the exchange current density) is several orders of magnitudes lower than that of HER. [5,6] As a consequence, the conversion and selectivity of these NRR electrocatalysts have remained prohibitively low.From a kinetic point of view, the key bottleneck for this electrochemical reaction to proceed should rely on the realization of highly efficient electrocatalysts that can not only process NRR effectively, but also limit the water reduction under this condition. [7] Nonetheless, most of the NRR electrocatalysts reported to date are prone to bind water molecules or protons. Ionic liquids, [8] organic solvents, [9] or solid-state proton conductors under high temperatures [10] have also been used to inhibit the HER and to improve the faradaic efficiency of ammonia production (FE NH3 ) to ≈60%. [8] However, these approaches are even more expensive than the traditional Haber-Bosch reaction and not capable of being implemented for large-scale deployment.Theoretical calculations [11] have proposed that several oxides, including the (110) facets of NbO 2 , ReO 2 , and TaO 2 , are potentially excellent NRR electrocatalysts, due to their reasonably high capability for nitrogen reduction to ammonia while simultaneously suppressing the competing water reduction. As NbO 2 is near the top of the volcano plot of potential determining step for electrochemical NRR against the binding energy of *NNH and it is relatively low cost, NbO 2 is considered to be a promising NRR electrocatalyst. A more recent study reported that Nb 2 O 5 nanofiber can serve as a good NRR electrocatalyst with a high FE NH3 of 9.26%. [12] Nonetheless, such an efficiency is still far from the demand for practical electrochemical ammonia synthesis powered by renewable energy like solar power. [7] In this work, we demonstrate that NbO 2 containing Nb 4+ can act as a highly efficient NRR electrocatalyst for ambient ammonia synthesis. Compared to the Nb 2 O 5 counterpart, NbO 2 exhibits both higher FE and production rate of ammonia in an acidic electrolyte, reaching the highest FE NH3 of 32% at −0.6 V versus reversible hydrogen electrode (RHE) and the highest ammonia yield rate of 11.6 µg h −1 mg cat.−1 at −0.65 V versus RHE. The excellent NRR performance of NbO 2 can be attributed to the The electrocatalytic N 2 reduction reaction (NRR) to produce ammonia is an attractive but highly challenging approach, due to the extreme inertness of N 2 molecules and significantly lower N 2 concentration compared to the surrounding water molecules. Herein, NbO 2 nanoparticles are demonstrated as an efficient NRR electrocatalyst with significantly improved electrochemical performances. Compared to Nb 2 O 5 with a similar crystal structure unit but different linkage, the Nb 4+ cation not only provides empty d-orbitals for strong N 2 adsorption, but also a single d-ele...

Tin alloying is a promising strategy to reduce lead content in metal halide perovskites solar cells and to modulate the perovskite band gap. Mixed tin−lead perovskites have shown photovoltaic efficiencies approaching those of lead perovskites and improved long-term stability compared to that of pure tin perovskites. We here demonstrate that the recent success of mixed perovskites lies in a composition-dependent struggle between tin and iodine chemistry at the material's surface. Tin oxidation, which plagues tin perovskite-based devices with low efficiency and thermodynamic instability, is hindered in mixed MAPb 0.5 Sn 0.5 I 3 by the competition with oxidation of iodine-related defects, the latter being generally favored by both thermodynamics and kinetics. Tin oxidation can be promoted, however, under Sn-poor conditions. When Sn is alloyed to Pb in low concentrations, it acts as a dopant and Sn(IV) is promptly formed on the perovskite surface.

Low-dimensional metal halide perovskites are being intensively investigated because of their higher stability and chemical versatility in comparison to their 3D counterparts. Unfortunately, this comes at the expense of the electronic and charge transport properties, limited by the reduced perovskite dimensionality. Cation engineering can be envisaged as a solution to tune and possibly further improve the material’s optoelectronic properties. In this work, we screen and design new electronically active A-site cations that can promote charge transport across the inorganic layers. We show that hybridization of the valence band electronic states of the perovskite inorganic sublattice and the highest occupied molecular orbitals of the A-site organic cations can be tuned to exhibit a variety of optoelectronic properties. A significant interplay of A-cation size, electronic structure, and steric constraints is revealed, suggesting intriguing means of further tuning the 2D perovskite electronic structure toward achieving stable and efficient solar cell devices.

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