2 research outputs found
Graphene-Based Standalone Solar Energy Converter for Water Desalination and Purification
Harvesting
solar energy for desalination and sewage treatment has
been considered as a promising solution to produce clean water. However,
state-of-the-art technologies often require optical concentrators
and complicated systems with multiple components, leading to poor
efficiency and high cost. Here, we demonstrate an extremely simple
and standalone solar energy converter consisting of only an as-prepared
3D cross-linked honeycomb graphene foam material without any other
supporting components. This simple all-in-one material can act as
an ideal solar thermal converter capable of capturing and converting
sunlight into heat, which in turn can distill water from various water
sources into steam and produce purified water under ambient conditions
and low solar flux with very high efficiency. High specific water
production rate of 2.6 kg h<sup>–1</sup> m<sup>–2</sup> g<sup>–1</sup> was achieved with near ∼87% under 1
sun intensity and >80% efficiency even under ambient sunlight (<1
sun). This scalable sheet-like material was used to obtain pure drinkable
water from both seawater and sewage water under ambient conditions.
Our results demonstrate a competent monolithic material platform providing
a paradigm change in water purification by using a simple, point of
use, reusable, and low-cost solar thermal water purification system
for a variety of environmental conditions
Photoprompted Hot Electrons from Bulk Cross-Linked Graphene Materials and Their Efficient Catalysis for Atmospheric Ammonia Synthesis
Ammonia
synthesis is the single most important chemical process
in industry and has used the successful heterogeneous Haber–Bosch
catalyst for over 100 years and requires processing under both high
temperature (300–500 °C) and pressure (200–300
atm); thus, it has huge energy costs accounting for about 1–3%
of human’s energy consumption. Therefore, there has been a
long and vigorous exploration to find a milder alternative process.
Here, we demonstrate that by using an iron- and graphene-based catalyst,
Fe@3DGraphene, hot (ejected) electrons from this composite catalyst
induced by visible light in a wide range of wavelength up to red could
efficiently facilitate the activation of N<sub>2</sub> and generate
ammonia with H<sub>2</sub> directly at ambient pressure using light
(including simulated sun light) illumination directly. No external
voltage or electrochemical or any other agent is needed. The production
rate increases with increasing light frequency under the same power
and with increasing power under the same frequency. The mechanism
is confirmed by the detection of the intermediate N<sub>2</sub>H<sub>4</sub> and also with a measured apparent activation energy only
∼1/4 of the iron based Haber–Bosch catalyst. Combined
with the morphology control using alumina as the structural promoter,
the catalyst retains its activity in a 50 h test