A Scalable Nickel–Cellulose Hybrid Metamaterial with Broadband Light Absorption for Efficient Solar Distillation

Abstract

absorbers have aroused great attention due to their resonant absorption and localized heating effect. [7][8][9] Nevertheless, this resonant absorption inherently features a narrow bandwidth, which is usually advantageous for applications such as biosensors [10] and resonant energy transfer, [11] but disadvantageous for broadband light absorption. [12,13] Some complex and delicate plasmonic metastructures were thus designed to hybridize proximate surface plasmons [12] or to support multiple resonances [13] in order to broaden the absorption bandwidth. However, the noble metals (i.e., Au and Ag) for plasmonic absorption along with the complicated fabrication procedures are undesirable for large-scale and full-spectrum (300-2500 nm) solar energy harvesting. [14] Zhou et al. creatively fabricated an all-aluminum hybrid plasmonic membrane, which was lowcost and enabled efficient broadband solar absorption. [15] The broadband plasmonic absorber was based on closely packed Al nanoparticles along the side walls of nanopores to induce a plasmon hybridization effect and high-density plasmonic resonances. [15] Among the several mechanisms that cause light absorption in metals, [16] interband transitions (IBTs) are single-electron excitations [17] from occupied levels in one band to unoccupied levels in another band, [18] in contrast to the collectively coherent excitation of electrons for plasmonic absorption. [19] IBTs intrinsically have a broadband attribute because photons the energy of which surpasses the interband threshold of a metal can excite IBTs. This makes IBTs very suitable for full-spectrum solar energy utilization, especially when massive IBTs over the entire solar spectrum can be supported by some transition metals (e.g., Ni, Pd, and Pt) with a high density of electronic states (DOS) near their Fermi levels. [20][21][22] In this work, we designed a Ni-cellulose hybrid metamaterial (NCM) that employs IBTs as the dominant optical absorption mechanism over the entire solar spectrum (Figures S1 and S2, and Note S1 for the detailed demonstration, Supporting Information). Nickel supports strong IBTs in very low energy regions (≈0.5 eV), which greatly increase optical absorption in the near-infrared spectrum compared to plasmonic metals (Au, Ag, and Cu). We densely embedded Ni nanoparticles into the nanogaps of cellulose microfibers via a seed-mediated and nanoconfined growth. This nanoconfinement effect can inhibit Sophisticated metastructures are usually required to broaden the inherently narrowband plasmonic absorption of light for applications such as solar desalination, photodetection, and thermoelectrics. Here, nonresonant nickel nanoparticles (diameters < 20 nm) are embedded into cellulose microfibers via a nanoconfinement effect, producing an intrinsically broadband metamaterial with 97.1% solar-weighted absorption. Interband transitions rather than plasmonic resonance dominate the optical absorption throughout the solar spectrum due to a high density of electronic states near the Fermi level of nickel. Fiel...

Intensifying Heat Using MOF‐Isolated Graphene for Solar‐Driven Seawater Desalination at 98% Solar‐to‐Thermal Efficiency

“…The maximum surface temperature and the near‐perfect efficiency of G@ZIF surpass most of the previously reported photothermal material (Table S1, Supporting Information). [ 38–42 ]…”

“…The maximum surface temperature and the near-perfect efficiency of G@ZIF surpass most of the previously reported photothermal material (Table S1, Supporting Information). [38][39][40][41][42] To evaluate the solar-to-vapor conversion performance, we place our G@ZIF steam generator directly on the bulk water surface and record both the surface temperature and the change in water weight over time upon light illumination. When the light is switched on, G@ZIF enables rapid photothermal conversion and water evaporates immediately at an evaporation rate of ≈1.78 kg m −2 h −1 , which is ≈8-fold higher than pure water in the absence of G@ZIF (0.24 kg m −2 h −1 ) under identical illumination conditions (Figure 4C and Figure S26A, Supporting Information).…”

Conjugated Acetylenic Polymers Grafted Cuprous Oxide as an Efficient Z‐Scheme Heterojunction for Photoelectrochemical Water Reduction

“…The formation of nanocopper is mostly due to the growth confinement by the nanogaps between the cellulose nanofibrils, preventing the further growth from copper nanocrystal to bulk copper (Figure S2, Supporting Information). [ 39,40 ] In view of the crystal growth, the tower‐like nanocopper structure on the Cu CP is self‐formable and dynamically stable. [ 41 ] Next, the pDET (Figure S3, Supporting Information), was in situ grown on a Cu CP (1 × 3 cm 2 ) via a 3 h‐Glaser polycondensation at 60 °C in a pyridine solution containing DET monomers (0.25 mg mL −1 ) and piperidine (4 µL mL −1 ) (Figure 1a).…”

Simple Hierarchical Interface Design Strategy for Accelerating Solar Evaporation

“…The first approach is to develop various photothermal materials with broadband optical absorption across the full solar radiation spectrum. [ 1 ] For example, metal nanoparticles, [ 18,19 ] carbon‐based materials, [ 7,13,20 ] metal oxides, [ 21 ] and polymers [ 22,23 ] possess high light absorption across the full solar radiation spectrum. Although, different types of photothermal materials have different photothermal conversion capabilities, the light absorption of these materials also depends on their morphology and structure.…”