Hierarchical Graphene Foam for Efficient Omnidirectional Solar–Thermal Energy Conversion

TLDR

Efficient solar‑thermal energy conversion is essential for harvesting abundant solar energy, yet graphene‑based materials with superior omnidirectional light‑harvesting performance remain elusive. The study aims to develop a hierarchical graphene foam that dramatically enhances broadband and omnidirectional solar absorption to elevate temperature. The foam is fabricated by plasma‑enhanced chemical vapor deposition, producing continuous porosity that boosts broadband absorption. The resulting material achieves an external solar‑thermal conversion efficiency of ≈93.4 % and a solar‑vapor conversion efficiency exceeding 90 % for seawater desalination with high endurance.

Abstract

Efficient solar-thermal energy conversion is essential for the harvesting and transformation of abundant solar energy, leading to the exploration and design of efficient solar-thermal materials. Carbon-based materials, especially graphene, have the advantages of broadband absorption and excellent photothermal properties, and hold promise for solar-thermal energy conversion. However, to date, graphene-based solar-thermal materials with superior omnidirectional light harvesting performances remain elusive. Herein, hierarchical graphene foam (h-G foam) with continuous porosity grown via plasma-enhanced chemical vapor deposition is reported, showing dramatic enhancement of broadband and omnidirectional absorption of sunlight, which thereby can enable a considerable elevation of temperature. Used as a heating material, the external solar-thermal energy conversion efficiency of the h-G foam impressively reaches up to ≈93.4%, and the solar-vapor conversion efficiency exceeds 90% for seawater desalination with high endurance.