Nanostructured carbon materials are potentially of great technological interest for the development of electronic, catalytic and hydrogen-storage systems. Here we describe a general strategy for the synthesis of highly ordered, rigid arrays of nanoporous carbon having uniform but tunable diameters (typically 6 nanometres inside and 9 nanometres outside). These structures are formed by using ordered mesoporous silicas as templates, the removal of which leaves a partially ordered graphitic framework. The resulting material supports a high dispersion of platinum nanoparticles, exceeding that of other common microporous carbon materials (such as carbon black, charcoal and activated carbon fibres). The platinum cluster diameter can be controlled to below 3 nanometres, and the high dispersion of these metal clusters gives rise to promising electrocatalytic activity for oxygen reduction, which could prove to be practically relevant for fuel-cell technologies. These nanomaterials can also be prepared in the form of free-standing films by using ordered silica films as the templates.

Herein we report that silicon nanowires (SiNWs) fabricated via metal-catalyzed electroless etching yielded a photoelectrochemical hydrogen generation performance superior to that of a planar Si, which is attributed to a lower kinetic overpotential due to a higher surface roughness, favorable shift in the flat-band potential, and light-trapping effects of the SiNW surface. The SiNW photocathode yielded a photovoltage of 0.42 V, one of the highest values ever reported for hydrogen generation on p-type Si/electrolyte interfaces.

The synthetic route and properties of three 2D hybrid organic/inorganic lead iodide perovskite materials are reported. The 2D perovskites were synthesized from the reaction between PbI 2 and the di-cations of 1,4diaminobutane, 1,6-diaminohexane, and 1,8-diaminooctane. The resulting products were [NH 3 (CH 2 ) 4 NH 3 ] PbI 4 (BdAPbI 4 ), [NH 3 (CH 2 ) 6 NH 3 ]PbI 4 (HdAPbI 4 ), and [NH 3 (CH 2 ) 8 NH 3 ]PbI 4 (OdAPbI 4 ). Structural characterization shows that two dimensional perovskite structures were formed with inorganic structural planes separated by organic layers. Absorption spectra show band gaps of 2.37 eV (BdAPbI 4 ), 2.44 eV (HdAPbI 4 ), and 2.55 eV (OdAPbI 4 ). The 2D perovskite materials were investigated as light absorbing materials in solid state solar cells.The best performing material under moist, ambient conditions was BdAPbI 4 (1.08% efficiency), which was comparable to methylammonium Pb(II) iodide (MAPbI 3 ) solar cells (2.1% efficiency) manufactured and studied under analogous conditions. When compared to MAPbI 3 , the 2D materials have larger band gaps and lower photoconductivity, while BdAPbI 4 based solar cells shows a comparable absorbed photon-to-current efficiency as compared to MAPbI 3 based ones. † Electronic supplementary information (ESI) available: Tables S1-S4 including atomic parameters of the structure of the three new materials, Fig. S1 and S2, two 2D structures of butyl 1,4-diammonium lead iodide and octyl 1,8-diammonium lead iodide along the three crystallographic axes. Tables S5-S11 and Fig. S3-S9 describe structural and photochemical characterization. CIF les for the structures are available at the Cambridge Crystallographic Data Center (CCDC) referring to the deposition numbers 1420433 and 1420434 for HdAPbI 4 and OdAPbI 4 , respectively. See

Herein we report on integrated photoelectrolysis of water employing organic metal halide (OMH) perovskite material. Generic OMH perovskite material and device architecture are highly susceptible to degradation by moisture and water. We found that decomposition of perovskite devices proceeds by water ingress through pinholes in upper layers and is strongly affected by applied bias/light and electrolyte pH. It was also found that a pinhole-free hole transport layer (HTL) could significantly enhance the stability of the perovskite photoelectrode, thereby extending the photoelectrode lifetime to several tens of minutes, which is an unprecedented record-long operation. Furthermore, a carbon nanotube (CNT)/polymer composite layer was developed that can effectively protect the underlying perovskite layer from electrolyte molecules.

Pt monolayer decorated gold nanostructured film on planar p-type silicon is utilized for photoelectrochemical H2 generation in this work. First, gold nanostructured film on silicon was spontaneously produced by galvanic displacement of the reduction of gold ion and the oxidation of silicon in the presence of fluoride anion. Second, underpotential deposition (UPD) of copper under illumination produced Cu monolayer on gold nanostructured film followed by galvanic exchange of less-noble Cu monolayer with more-noble PtCl6(2-). Pt(shell)/Au(core) on p-type silicon showed the similar activity with platinum nanoparticle on silicon for photoelectrochemical hydrogen evolution reaction in spite of low platinum loading. From Tafel analysis, Pt(shell)/Au(core) electrocatalyst shows the higher area-specific activity than platinum nanoparticle on silicon demonstrating the significant role of underlying gold for charge transfer reaction from silicon to H(+) through platinum catalyst.