A facile synthesis strategy to control the porosity of ionothermal nitrogen doped carbons is demonstrated. Adenine is used as cheap and biomass based precursor and a mixture of NaCl/ZnCl2 as combined solvent-porogen. Variation of the ratio between the two salt influences the pore structure over a wide range. The eutectic mixture leads to micro- and mesoporous material with high total pore volume (TPV) of 3.0 cm3 g−1 and very high surface area of 2900 m2 g−1 essentially rendering the product an “all-surface-area” nitrogen doped carbon. Increasing NaCl contents cause a continuous increase of the mesopore size and the formation of additional macropores resulting in a very high maximal TPV of 5.2 cm3 g−1, showing 2540 m2 g−1 specific surface area using 60 mol% NaCl. Interestingly, the electrocatalytic activity of the samples toward oxygen reduction is strongly affected by the detailed pore structure. The different—however, chemically equivalent—catalysts vary up to 70 mV in their half wave potentials (E 1/2).The sample with optimized pore system shows a high selectivity toward the favored four electron process and an outstanding E 1/2 of ≈880 mV versus reversible hydrogen electrode (RHE), which is one of the best values reported for nitrogen doped carbons so far

Layered V 2 O 5 hydrate has been applied as the hole transport layer (HTL) in organic solar cells (OSCs). V 2 O 5 is obtained from a sodium metavanadate solution in water under ambient conditions, resulting in a final thin film of formula V 2 O 5 $0.5H 2 O. The 0.5 water molecules are not removed from the V 2 O 5 layered structure unless the sample is heated above 250 C, which makes the thin film highly stable under real working conditions. The HTL was used in OSCs in the normal and the inverted configurations, applying metallic Ag as the back-metal electrode in both cases. Fabrication of both OSC configurations completely by solution-processing printing methods in air is possible, since the Al electrode needed for the normalconfiguration OSC is not required. The work function (WF) and band gap energy (BG) of the V 2 O 5 thin films were assessed by XPS, UPS and optical analyses. Different WF values were observed for V 2 O 5 prepared from a fresh V 2 O 5-isopropanol (IPA) solution (5.15 eV) and that prepared from a 24 hold solution (5.5 eV). This difference is due to the gradual reduction of vanadium (from V 5+ to V 4+) in IPA. The OSCs made with the V 2 O 5 thin film obtained from the 24 hold V 2 O 5-IPA solution required photoactivation, whereas those made with the freshly obtained V 2 O 5 did not. Outdoor stability analyses of sealed OSCs containing a V 2 O 5 HTL in either configuration revealed high stability for both devices: the photovoltaic response at T 80 was retained for more than 1000 h. Broader context Organic Solar Cells (OSCs) have achieved an impressive increase in power conversion efficiency in the past few years, with values above the 12% range. Yet, in order to be competitive with existing energy sources from fossil fuels and modern inorganic photovoltaic technologies, OSCs must reduce fabrication costs and improve its energy payback time (EPBT). To achieve the latter, the fabrication of OSCs by large scale, solution processing methods applying inexpensive, low temperature techniques is required. An important aim is the exclusion of toxic organic solvents, being water-based or alcohol-based solutions is highly desired. In this work, a layered V 2 O 5 hydrate has been applied as the hole transport layer in stable OSCs. V 2 O 5 is obtained from the dissolution of sodium metavanadate in water under ambient atmospheric conditions, resulting in a nal thin lm with the V 2 O 5 $0.5H 2 O formula. OSCs with normal and inverted conguration applying metallic Ag as the back metal electrode in both cases have been fabricated. The use of a Ag electrode eliminates the need for a highly reactive work function metal electrodes (Al, Ca) for the normal conguration OSC, and permits the fabrication of both OSC congurations completely by solution processing printing methods in air. Outdoor stability analyses of sealed devices showed high stability, maintaining the photovoltaic response at T 80 for more than 1000 h.

The use of lignin as a precursor for the synthesis of materials is nowadays considered very interesting from a sustainability standpoint. Here we illustrate the synthesis of a micro-, meso-, and macroporous nitrogen-doped carbon (NDC) using lignin extracted from beech wood via alkaline hydrothermal treatment and successively functionalized via aromatic nitration. The so obtained material is thus carbonized in the eutectic salt melt KCl/ZnCl2. The final NDC shows an excellent activity as electrocatalyst for the oxygen reduction reaction.