Molecular implantation using a laser-induced molecular micro-jet

Implantation of organic molecules into conductive organic or inorganic materials on the nanometre scale is one of the challenging problems in materials research that has to be solved. We have developed an advanced method of laser implantation suitable for producing organic molecular dots with sizes of a few hundred nanometres on organic and inorganic solid materials. This method involves transferring of organic molecules from a source film to a target material through a water-filled space-gap using a laser-induced molecular micro-jet. In this way, organic dots of Coumarin 6 (C6) molecules were successfully implanted into different target materials such as polymer, glass, copper, indium tin oxide (ITO), stainless steel, and so on. The shapes of the implanted dots as well as the shapes of the holes, caused by damage to the source or target films during laser irradiation, depended on whether water or air filled the space-gap between the films

Efficient and stable visible-light-driven Z-scheme overall water splitting using an oxysulfide H2 evolution photocatalyst

Abstract So-called Z-scheme systems permit overall water splitting using narrow-bandgap photocatalysts. To boost the performance of such systems, it is necessary to enhance the intrinsic activities of the hydrogen evolution photocatalyst and oxygen evolution photocatalyst, promote electron transfer from the oxygen evolution photocatalyst to the hydrogen evolution photocatalyst, and suppress back reactions. The present work develop a high-performance oxysulfide photocatalyst, Sm2Ti2O5S2, as an hydrogen evolution photocatalyst for use in a Z-scheme overall water splitting system in combination with BiVO4 as the oxygen evolution photocatalyst and reduced graphene oxide as the solid-state electron mediator. After surface modifications of the photocatalysts to promote charge separation and redox reactions, this system is able to split water into hydrogen and oxygen for more than 100 hours with a solar-to-hydrogen energy conversion efficiency of 0.22%. In contrast to many existing photocatalytic systems, the water splitting activity of the present system is only minimally reduced by increasing the background pressure to 90 kPa. These results suggest characteristics suitable for applications under practical operating conditions

Elucidating the Role of Surface Energetics on Charge Separation during Photoelectrochemical Water Splitting

Efficient photoelectrochemical (PEC) water splitting requires charge separation and extraction from a photoactive semiconductor. Such a charge transport process is widely believed to be dictated by the bulk energetics of the semiconductor. However, its dependence on surface energetics along the semiconductor/electrolyte interface remains an open question. Here, we elucidate the influence of surface energetics on the performance of a well-established Mo-doped BiVO4 photoanode whose surface energetics are regulated by the facet-selective cocatalyst loading. Surprisingly, photodeposition of RhOx and CoOx cocatalysts onto the {010} and {110} facets, respectively, strongly enhanced the charge-separation efficiency, in addition to improving the injection efficiency for water oxidation. Detailed optoelectrical simulations confirm that the synergistic enhancement of charge separation originates from the distinct effects of the cocatalyst loading on the surface energetics. This insight into the fundamental charge-separation mechanism in PEC cells provides a perspective for cell design and operation