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Abstract H 2 is clean power source, which can be obtained from hydrogen evolution reaction (HER) through electrocatalysis directly. To obtain highly effective electrocatalyst with low price for HER, small Mo 2 C nanoparticles with dimension about 4–6 nm were loaded on rice paper derived nitrogen doped 3D mesoporous carbon matrix with ammonium heptamolybdate as precursor after calcination. The unique 3D mesoporous carbon matrix donates the electrocatalyst large surface as well as high conductivity, which enhances HER activity in great extent. In 0.5 M H 2 SO 4 , to obtain the current with density 10 mA cm−2, the electrocatalyst only requires overpotential of 155 mV with Tafel slope merely 73 mV·dec−1. In 1.0 M KOH, these values decrease to 78 mV and 64 mV·dec−1. Moreover, this electrocatalyst also exhibits outstanding stability and its activity keeps stable after 2000 runs 10 h long-time tests. In 0.5 M H 2 SO 4 , the H 2 production rate of this electrocatalyst achieves 456 μmol h−1. The faradaic efficiency this electrocatalyst arrives nearly 100% in both acidic and basic conditions. This work introduces a new and efficient strategy to fabricate noble metal free HER electrocatalyst with cheap material as precursor. The simple preparation procedure facilitates the application of this electrocatalyst in HER. Graphical abstract A Mo 2 C based composite electrocatalyst has been fabricated successfully with (NH 4) 6 Mo 7 O 24 ·4H 2 O and rice paper as precursor for HER. Image 1 Highlights • Rice paper was employed as precursor to synthesis composite electrocatalyst. • 3D mesoporous nitrogen doped carbon matrix has been obtained. • The composite electrocatalyst exhibits HER excellent activity. • During H 2 production process, the faradaic efficiency achieves almost 100%. [ABSTRACT FROM AUTHOR]

Abstract It is known that some components of the bathing solution can enhance water splitting at depleted solution/ion-exchange membrane interface via protonation/deprotonation reactions with water. In this paper, we show that not only the presence of such components is important, but also a mechanism ensuring their sufficiently high concentration near the membrane surface. A comparative study of the electrochemical behavior of a Neosepta® homogeneous cation-exchange CMX and an anion-exchange AMX membranes (Astom, Japan) in 0.02 M KCl or 0.02 M NH 4 Cl solutions is carried out. The NH 4 +/NH 3 couple is an effective catalyst of water splitting. The deprotonation reaction rate constant of the NH 4 + ions, which limits the rate of water splitting, is about 10 s−1. It is almost 6 orders of magnitude greater than the rate constant for direct water dissociation in free solution. A comprehensive electrochemical characterization of the membrane systems is made: voltammetry, chronopotentiometry, electrochemical impedancemetry, and pH-metry (including color indication of the pH of the membrane internal solution). It is found that the water splitting rate at the interface of the AMX membrane in the NH 4 Cl solution is essentially higher than in the KCl solution. The difference in the rates of this reaction in KCl and NH 4 Cl solutions at the CMX membrane is insignificant. The reason for the weak effect of the NH 4 +/NH 3 couple on the rate of water splitting at the CMX membrane is that the concentration of both NH 4 + and NH 3 species is very low near its surface if the current density is close to or higher than its limiting value. As for the AMX membrane, we show that the ammonia-containing species can be transported to its depleted surface from the enriched solution by back "facilitated" diffusion through the membrane and this transport plays a crucial role in the occurrence of the rapid water splitting. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a novel one-step solution approach is developed to prepare high quality methylammonium lead trihalide (MAPbI 3) perovskite films. This approach employs methanol as additive, which is added into the perovskite precursor solution. The use of methanol can enhance the absorption of MAPbI 3 and significantly improve the coverage of MAPbI 3 on a planar substrate. The fabricated perovskite solar cell (PSC) with methanol exhibits a higher power conversion efficiency (PCE) compared with that without methanol (19.51% vs 16.53%). Furthermore, the power conversion efficiencies of devices with methanol are still high after kept in dark under ambient environment for 30 days. This work provides a method to prepare high quality perovskite films for planar perovskite solar cells with high performance. Graphical abstract A novel one-step solution is reported to prepare perovskite films by adding methanol into the perovskite precursor solution. The use of methanol can enhance the absorption of CH 3 NH 3 PbI 3 and significantly improve the coverage of CH 3 NH 3 PbI 3 on a planar substrate. The fabricated perovskite solar cell with methanol exhibits a higher power conversion efficiency compared with that without methanol (19.51% vs 16.53%). Image 1 Highlights • Methanol was employed as additive successfully for perovskite solar cells. • The methanol-treated PSCs showed remarkable efficiency and enhanced stability. • The methanol-treated method can suppress the hysteresis. [ABSTRACT FROM AUTHOR]

Abstract In order to optimize microstructure and improve the photoelectric properties of planar perovskite solar cells (PSCs), the Cs+ and SCN− are selected to tune the A-site cation and X-site anion composition of CH 3 NH 3 PbI 3 material with ABX 3 structure, respectively. The effects of Cs+ and SCN− addition on the microstructure and photoelectric properties of (CH 3 NH 3) 0.9 Cs 0.1 Pb(I 1-x SCN x) 3 perovskite films and the performance of PSCs have been systematically investigated. The value of "x" corresponding to the amount of SCN− has been optimized. At the optimum amount of 0.05, the (CH 3 NH 3) 0.9 Cs 0.1 Pb(I 0.95 SCN 0.05) 3 (Cs 0.1 SCN 0.05) PSC achieve the champion power conversion efficiency (PCE) of 18.78% and average PCE of 17.66%, being much higher than that of the reference PSCs. The results indicate that the obtained Cs 0.1 SCN 0.05 perovskite film shows the improved microstructure, better local electric properties, the reduced trap density and suppressed charge recombination, resulting in the promoted carrier transfer and improved performance in PSCs. [ABSTRACT FROM AUTHOR]