Phonon-Engineered Hard-Carbon Nanoflorets Achieving Rapid and Efficient Solar-Thermal Based Water Evaporation and Space-Heating

Abstract

Generation and utilization of green heat produced from solar energy demand broadband absorbers with the elusive combination of strong phonon-driven photon thermalization and, contrastingly, weak phonon-lattice thermal conductivity. Here, we report a new class of porous, nanostructured hard-carbon florets (NCFs) consisting of isotropically assembled conical microcavities for greater light entrapment and efficient broad-band absorption (95% over 250−2500 nm). Resembling marigolds, the NCF exhibits short-range graphitic order that promotes instantaneous and efficient solar-thermal conversion (η STC = 87%) while exhibiting long-range intrinsic disorder providing low thermal conductivity (1.5 W m −1 K −1 ) to minimize thermal loss (13%). Solution processable NCF coatings on arbitrarily substrates (filter paper, terracotta, Cu and Al tubes) generate surface temperature of 400 ± 2 K and exhibit high thermal effusance (519 W s 0.5 m −2 K −1 ) to achieve highest combination of (a) rate of solar-driven interfacial water evaporation (R w = 5.4 kg m −2 h −1 , 2 sun), (b) solar-vapor conversion efficiency (η SVC = 186%), and (c) η STC (87%) among known materials. Such robust performance is retained for beyond 30 days of continuous operation and under different solar power (1 sun to 5 sun). Furthermore, active space heating (outlet air temperature = 346 ± 3 K) using NCF coatings is demonstrated.

Zn, Fe Dual-Atom Sites Catalyst Constructed by Metal Vacancy Strategy for Oxygen Reduction Reaction and Zn-Air Battery

“…Raman spectroscopy was employed to evaluate the graphitization degree of carbons (Figure S7), where the Dband (1351 cm −1 ) and G-band (1594 cm −1 ), respectively, stand for the defective and graphitized carbon. 57,58 The ratio between D-band and G-band is often utilized to investigate the graphitization degree of carbons. 59,60 It is apparent that the increase of the secondary pyrolysis temperature (I D /I G : Zn, Fe/NC-700 > Zn/NC > Zn, Fe/NC-800 > Zn, Fe/NC-900 > Zn, Fe/NC-1000 = 1.23 > 1.20 > 1.19 > 1.14 > 1.01) can enhance the graphitization of carbons.…”

“…The effect of different pyrolysis temperatures on Zn, Fe/NC was also explored (Figure S6) and it reveals that when the pyrolysis temperature reaches 900 and 1000 °C, the aggregation of catalysts becomes more serious. Raman spectroscopy was employed to evaluate the graphitization degree of carbons (Figure S7), where the D-band (1351 cm –1 ) and G-band (1594 cm –1 ), respectively, stand for the defective and graphitized carbon. , The ratio between D-band and G-band is often utilized to investigate the graphitization degree of carbons. , It is apparent that the increase of the secondary pyrolysis temperature ( I D / I G : Zn, Fe/NC-700 > Zn/NC > Zn, Fe/NC-800 > Zn, Fe/NC-900 > Zn, Fe/NC-1000 = 1.23 > 1.20 > 1.19 > 1.14 > 1.01) can enhance the graphitization of carbons. However, the differences in graphitization degree between catalysts are not obvious.…”

Interface Engineered Hard-Carbons as Subsurface Hydrogen Reservoir for Accelerated and Highly Selective Olefin Hydrogenation with Favorable Sustainability Metrics

“…The NCF (mean diameter ∼400 ± 5 nm) thus obtained exhibits a high specific surface area (886 m 2 /g), composed of a combination of micro and mesoporous network, resulting in an average pore volume of 0.6 cm 3 /g (Figure S5). ,,, Thus, the combination of higher specific surface area, smaller pore diameter with graded porosity and expanded d -spacing (detailed below) offer distinct advantages in NCF over other catalyst supports. , …”

“…The open-ended, well-separated lamellae of NCF were prepared using dendritic fibrous nano silica (DFNS) as a template following an established protocol (refer to Supporting Information for details of preparation method). − The as-prepared NCF was used as a catalyst support to prepare Pt-based nanostructured catalysts in two different approaches, PON and PIN. To fabricate the PON catalyst, 10 mg of NCF was mixed with 50 mL of 0.1 mM aqueous solution of chloroplatinic acid hydrate and stirred continuously at approximately 600 rpm for 5–6 h. The metal-loaded NCF suspension was repeatedly washed with distilled water for 5–6 times and dried at 80 °C in a hot-air oven, followed by supercritical CO 2 drying overnight.…”