Honeycomb-shaped carbon nanotube supports for BiVO4 based solar water splitting.

Advances in the synthesis and assembly of nanomaterials offer a unique opportunity to purposefully design structures according to the requirements of the targeted applications. This paper shows a process to create robust 3D carbon nanotube (CNT) structures, which provide an electrically conductive support for nanoparticle coating. We describe a process to reliably fabricate robust honeycomb structures with walls made out of aligned CNTs. We present a design of experimental analysis of this fabrication process and discuss methods to coat these honeycombs with BiVO4 for solar fuel applications. The proposed honeycomb structure allows for an efficient transport of electrons through the electrode, as well as an enhanced light-electrode interaction. Finally, we demonstrate that the developed CNT electrodes can survive harsh BiVO4 synthesis conditions and can subsequently be used as photoelectrodes for solar water splitting

Vapor-fed solar hydrogen production exceeding 15% efficiency using earth abundant catalysts and anion exchange membrane

Vapor-fed solar hydrogen generators can convert water vapor from the air into hydrogen using sunlight as the energy source. Hydrogen and oxygen evolution reactions are performed in the gas phase in cathode and anode compartments separated by a membrane. Anion exchange membranes show great promise for this type of solar hydrogen generator. They provide an alkaline environment enabling the use of earth abundant materials as electrocatalysts. In this work, a vapor-fed solar hydrogen generator with KOH-doped poly(vinyl alcohol) anion exchange membrane flanked with NiFe and NiMo catalysts is demonstrated. The device reached an average 15.1% solar-to-hydrogen efficiency at room temperature and 95% relative humidity. This first demonstration of gas phase water splitting with earth abundant catalysts and anion exchange membrane opens a pathway to low cost, autonomous, efficient and safe solar hydrogen generators

Triple-Cation-Based Perovskite Photocathodes with AZO Protective Layer for Hydrogen Production Applications

Metal halide perovskites are actively pursued as photoelectrodes to drive solar fuel synthesis. However, currently, these photocathodes suffer from limited stability in water, which hampers their practical application. Here, we report a high-performance solution-processable photocathode composed of cesium formamidinium methylammonium triple-cation lead halide perovskite protected by an Al-doped ZnO (AZO) layer combined with a Field's metal encapsulation. Careful selection of charge transport layers resulted in an improvement in photocurrent, fill factor, device stability and reproducibility. The dead pixels count reduced from 25 to 6% for the devices with an AZO layer, and in photocathodes with an AZO layer the photocurrent density increased by almost 20% to 14.3 mA cm-2. In addition, we observed a 5-fold increase in the device lifetime for photocathodes with AZO, which reached up to 18 h before complete failure. Finally, the photocathodes are fabricated using low-cost and scalable methods, which have promise to become compatible with standard solution-based processes

Air-based photoelectrochemical cell capturing water molecules from ambient air for hydrogen production

A system is demonstrated that autonomously produces hydrogen gas using sunlight and outside air as the only inputs. Oxygen and hydrogen formation reactions occur on either side of a monolithic "solar membrane" inserted in a two-compartment photoelectrochemical cell. A surface film of Nafion® serves as a solid electrolyte. This proof of concept invites further development of air-based cells. © 2014 The Royal Society of Chemistry

Air-based photoelectrochemical cell capturing water molecules from ambient air for hydrogen production

A system is demonstrated that autonomously produces hydrogen gas using sunlight and outside air as the only inputs. Oxygen and hydrogen formation reactions occur on either side of a monolithic "solar membrane" inserted in a two-compartment photoelectrochemical cell. A surface film of Nafion® serves as a solid electrolyte. This proof of concept invites further development of air-based cells. © 2014 The Royal Society of Chemistry.status: publishe