The enhanced near-field amplitude of localized surface plasmon resonance in the proximity of metal nanoparticles can boost the photocatalytic activity of the neighboring semiconductor, which has been proven and has attracted wide interest recently. Since the plasmon resonance energy strongly depends on the metal particle size and shape, interparticle spacing, and dielectric property of the surrounding medium, it is available to improve the photocatalytic activity of the neighboring semiconductor by designing and synthesizing targeted metal nanoparticles or assembled nanostructures. In this paper, we propose a Au/TiO2/Au nanostructure with the thickness of the middle layer TiO2 nanosheets around 5 nm, which satisfies the distance needed for the coupling effect between the opposite and nearly touching Au nanoparticles, and thus, it can be used as a “plasmonic coupling photocatalyst”. Compared with the bare TiO2 nanosheet films, the photocurrent density of this favorable nanostructure exhibited a significant improvement in the visible region. The three-dimensional finite-difference time domain was used to quantitatively account for the electromagnetic enhancement of this Au/TiO2/Au heterostructure and substantiated the plasmonic enchancement photocatalytic mechanism further.

Fog harvesting is a useful technique for obtaining fresh water in arid climates. The wire meshes currently utilized for fog harvesting suffer from dual constraints: coarse meshes cannot efficiently capture microscopic fog droplets, whereas fine meshes suffer from clogging issues. Here, we design and fabricate fog harvesters comprising an array of vertical wires, which we call "fog harps". Under controlled laboratory conditions, the fog-harvesting rates for fog harps with three different wire diameters were compared to conventional meshes of equivalent dimensions. As expected for the mesh structures, the mid-sized wires exhibited the largest fog collection rate, with a drop-off in performance for the fine or coarse meshes. In contrast, the fog-harvesting rate continually increased with decreasing wire diameter for the fog harps due to efficient droplet shedding that prevented clogging. This resulted in a 3-fold enhancement in the fog-harvesting rate for the harp design compared to an equivalent mesh.

An artificial periodic roughness-gradient conical copper wire (PCCW) can be fabricated by inspiration from cactus spines and wet spider silks. PCCW can harvest fog on periodic points of the conical surface from air and transports the drops for a long distance without external force, which is attributed to dynamic as-released energy generated from drop deformation in drop coalescence, in addition to both gradients of geometric curve (inducing Laplace pressure) and periodic roughness (inducing surface energy difference). It is found that the ability of fog collection can be related to various tilt-angle wires, thus a fog collector with an array system of PCCWs is further designed to achieve a continuous process of efficient water collection. As a result, the effect of water collection on PCCWs is better than previous results. These findings are significant to develop and design materials with water collection and water transport for promising application in fogwater systems to ease the water crisis.

Smart anisotropic-unidirectional spreading is displayed on a wettable-gradient-aligned fibrous surface due to a synergetic directing effect from the aligned structure and the ratio of hydrophilic components.

Fog harvesting is useful for passively collecting fresh water in arid regions, but the efficiency of current mesh‐based harvesters is compromised by their poor drainage. Inspired by the linear needles of redwood trees, “fog harps” are developed whose array of vertical wires enables an unobstructed drainage pathway. A full‐scale (1 m2 frame) fog harp is fabricated by winding a stainless steel wire around a spinning aluminum frame featuring threaded rods. The fog harp is field tested for a full year at a local farm (Blacksburg, VA, USA), alongside the control case of a mesh harvester. Under moderate fog conditions, the fog harp collects anywhere from 2 to 78 times more water compared to the mesh harvesters. Under light fog conditions, the fog harp collects up to several hundred milliliters of water per day while the mesh is unable to collect any water at all. The water harvesting performance of fog harps is therefore unprecedented in two ways: they substantively elevate the performance ceiling when exposed to healthy fog while also enabling, for the first time, appreciable water harvesting under light fog.