This review describes an in-depth overview and knowledge on the variety of synthetic strategies for forming metal sulfides and their potential use to achieve effective hydrogen generation and beyond.

A drop of solution containing nonvolatile solute is allowed to evaporate from a sphere-on-flat geometry. Left behind is a striking pattern of gradient concentric rings with unprecedented regularity. The center-to-center distance between adjacent rings, lambda(C-C), and the height of the ring, h(d), are strongly affected by the concentration of the solution and the properties of the solvent. The nature of the formation of regular gradient ring patterns during the course of irreversible solvent evaporation is revealed through theoretical calculations based on the mass conservation of the solution.

Research into the evaporation of solutions is not only aimed at a better understanding the physics of evaporation, but increasingly at capitalizing on the extremely simple method it offers to assemble diverse nonvolatile solutes into complex ordered structures on the submicron and longer length scales. This Review highlights recent advances in evaporative assembly of confined solutions, focusing especially on recently developed approaches that provide structures with unprecedented regularity composed of polymers, nanoparticles, and biomaterials, by controlled evaporation‐driven, flow‐aided self‐assembly. A broad range of variables that can control the deposition are explored and the future directions of this rich field are presented.

TiO 2 nanotube arrays (TNTAs) sensitized by palladium quantum dots (Pd QDs) exhibit highly efficient photoelectrocatalytic hydrogen generation. Vertically oriented TNTAs were prepared by a three-step electrochemical anodization. Subsequently, Pd QDs with uniform size and narrow size distribution were formed on TiO 2 nanotubes by a modified hydrothermal reaction (i.e., yielding nanocomposites of Pd QDs deposited on TNTAs, Pd@TNTAs). By exploiting Pd@TNTA nanocomposites as both photoanode and cathode, a substantially increased photon-to-current conversion efficiency of nearly 100% at λ = 330 nm and a greatly promoted photocatalytic hydrogen production rate of 592 μmol·h −1 ·cm −2 under 320 mW·cm −2 irradiation were achieved. The synergy between nanotubular structures of TiO 2 and uniformly dispersed Pd QDs on TiO 2 facilitated the charge transfer of photoinduced electrons from TiO 2 nanotubes to Pd QDs and the high activity of Pd QDs catalytic center, thereby leading to high-efficiency photoelectrocatalytic hydrogen generation. P hotoelectrocatalytic water splitting is widely recognized as one of the most promising routes to large-scale production of hydrogen as a potential fuel for renewable energy.1 Among the various catalysts, the noble metal palladium has attracted much attention as one of the most versatile candidates utilized in hydrogen-relevant reactions.2 In particular, Pd immobilized on diverse supports, including carbon, silicates, amorphous or mesoporous silica, and porous biomaterials or polymers, exhibits remarkable performance in organic transformations and especially coupling and hydrogenation reactions.3−6 Onedimensional highly ordered TiO 2 nanotube arrays (TNTAs) fabricated by electrochemical anodization have been demonstrated as a promising photoanode for use in photocatalytic water splitting and solar energy conversion with markedly improved efficiency.7−13 Modified TNTAs were found to possess attractive activities for photoelectrocatalytic water splitting.14,15 However, due to the fast recombination of photogenerated electrons and holes, it remains a major challenge to successfully capitalize on TNTAs for photocatalytic applications.It is well known that the catalytic properties of composites of transition metal particles and supporting materials depend heavily upon the metal particle size, dispersion, composition, etc. 16,17 In this context, it is of high importance to prepare such composites with uniform dispersion, tunable particle size, and narrow size distribution to promote their catalytic activities. 18Catalysts made of Pd nanoparticles supported on TNTAs (i.e., Pd@TNTA nanocomposites) are expected to enhance TiO 2 photocatalysis for hydrogen generation; this can be ascribed to their prominent charge-transfer and separation properties and stability against photocorrosion. 19 The latter contrasts sharply with most of semiconductors, such as CdS, which cause photocorrosion and are not suitable for water splitting.19 As the Fermi level of Pd is lower than that of TiO 2 , photoex...

The controlled synthesis of nanohybrids composed of noble metals and metal oxides have received considerable attention for applications in photocatalysis, solar cells, drug delivery, surface enhanced Raman spectroscopy and many other important areas.