We use dip-pen nanolithography to accurately pattern Ni(OH)2 nanoclusters on a metachemical surface with an exceptionally large surface area. The distance between the nanoclusters can be manipulated to control the oxygen-evolution reaction current and overpotential, thereby improving the efficiency of the water-splitting process while using minute amounts of the catalyst.

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The demand for miniature, low-cost, utmost efficient optical absorbers triggered ongoing research efforts to minimize the overall design thickness, particularly the photo-active layer, while still maintaining a high optical absorptance....

Dip‐pen nanolithography (DPN) is a low‐cost, versatile bench‐top method for directly patterning materials on surfaces with sub‐50 nm resolution; it involves the use of a cantilever tip to transfer a selected ink onto various surfaces to create predefined patterns. Many parameters may influence DPN quality, due to the variety of deposited and surface materials and the chemical interactions between them. DPN tip deposition of liquid inks is not yet well understood, due to the lack of thorough study of the various parameters that need to be controlled in order to achieve uniform patterning. In this research, the printing of polydimethylsiloxane (PDMS) lines and the control of their physical dimensions are investigated; the applied parameters are different humidity levels, n‐hexane dilution proportions and different tip velocities. Numerous experiments accompanied by atomic force microscope measurements are conducted in order to derive a recommended recipe for the required dimensions of the printable lines. A practical aspect of the research is to assess the potential of the application of DPN for the fabrication of various optical devices, such as gratings and waveguides. In order to validate the theoretical results, PDMS printing over silicon is used to successfully produce an optical diffraction grating.

A new dielectric Fabry-Perot cavity was designed for a resonant enhancing optical absorption by a thin absorber layer embedded into the cavity. In this cavity, the front mirror is a subwavelength grating with ∼ 100% retroreflection. For a HgCdTe absorber in a matching cavity of the new type, the design is shown to meet the combined challenges of increasing the absorbing efficiency of the entire device up to ∼ 100 % and reducing its size and overall complexity, compared to a conventional resonant cavity enhanced HgCdTe absorber, while maintaining a fairly good tolerance against the grating's fabrication errors.Keywords Optical resonant cavity · Photodetectors · HgCdTe · Gratings Here λ 0 is a resonance wavelength n c and t c is the refractive index (RI) and length of the FP cavity, respectively, ϕ f and ϕ b are the reflection phase of the mirror that