NiFe nanoparticle electrocatalysts, supported on duckweed-derived carbon, splits water at 1.61 V and provides a 9.7% solar-to-hydrogen efficiency when connected to solar cells.
Grain boundaries in bulk perovskite films are considered as giant trapping sites for photo-generated carriers. Surface engineering via inorganic perovskite quantum dots has been employed for creating monolithically grained, pin-hole free perovskite films.
The
ambient stability, hysteresis, and trap states in organo-halide
perovskite solar cells (PSCs) are correlated to the influence of interlayer
interfaces and grain boundaries. Astute incorporation of Cu2ZnSnS4 (CZTS) and Au/CZTS core/shell nanocrystals (NCs)
can realize the goal of simultaneously achieving better performance
and ambient stability of the PSCs. With optimized Au/CZTS NC size
and concentration in the photoactive layer, power conversion efficiency
can be increased up to 19.97 ± 0.6% with ambient air stability
>800 h, as compared to 14.46 ± 1.02% for the unmodified devices.
Through efficient carrier generation by CZTS and perovskite, accompanied
by the plasmonic effect of Au, carrier density is sufficiently increased
as validated by transient absorption spectroscopy. NCs facilitate
the interfacial charge transfer by suitable band alignment and removal
of recombination centers such as metallic Pb0, surface
defects, or impurity sites. NC embedding also increases the perovskite
grain size and assists in pinhole filling, reducing the trap state
density.
Devices with ITO/ZnO/ZnS/CFTS/Au, ITO/ZnO/ZnS/CCTS/Au and ITO/ZnO/ZnS/CNTS/Au architectures exhibited PCE values of 2.73, 3.23 and 2.71% and displayed good electrocatalytic behaviors.
Two-dimensional
(2D) materials such as layered double hydroxides
(LDH) are promising electrocatalysts, especially for water oxidation,
owing to their unique physical and electronic properties besides having
adequate surface area and availability of unsaturated active metal
centers. Herein, we illustrate the high-temperature transformation
of bimetallic LDH to semicrystalline 2D metal oxide nanoplates that
can maneuver their electronic properties and thereby accelerate the
water dissociation reactions. The nanoplates prepared at 300 °C
require only 280 ± 13 and 177 ± 7 mV overpotentials for
oxygen/hydrogen evolution reactions (OER and HER) to achieve a current
density of ±10 mA cm–2 in 1 M KOH, respectively.
In a two-electrode water splitting cell, while this bifunctional catalyst
needs 1.69 V to deliver a current density of 10 mA cm–2, the LDH precursor demands a cell voltage of 1.93 V. However, both
the catalysts demonstrate excellent durability for more than 200 h.
When the bifunctional metal oxide electrolyzer is connected to perovskite
solar cells for unassisted solar-driven water splitting, impressively,
such an integrated photovoltaic-electrolyzer can achieve a solar-to-hydrogen
(STH) efficiency of 9.3%. The predominantly superior catalytic activity
of the nanoplates is due to the abundance of unsaturated oxygen which
decreases the free energy of adsorption of the intermediates.
The versatile optoelectronic properties of perovskite nanocrystals (NCs) have provided a strong surge for their utilization in different classes of solar cells, with organic photovoltaic systems being no exception. In an unprecedented approach, a hybrid solar cell with CsPbBr 1.5 I 1.5 NCs strategically grafted on poly(3-hexylthiophene-2,5-diyl) (P3HT) nanorods (NRs) is shown to have a photoconversion efficiency of 9.72 ± 0.4%, with only 1.5 wt % NCs. The improvement is twice more than the P3HT:PCBM reference devices (4.09 ± 0.2%). The choice of NC composition is validated by density functional theory calculations, which show decent charge carrier mobility in CsPbBr 1.5 I 1.5 , besides having better stability than CsPbI 3 , making CsPbBr 1.5 I 1.5 NCs a suitable contender for hybrid device architecture. A trivial blending of the NCs in the P3HT:PCBM matrix results in their nonuniform distribution, escalating charge carrier trapping, albeit maintaining a device efficiency of 8.07 ± 0.3% with 1 wt % NCs. Uniform NC grafting is propitious over inhomogeneous blending because CsPbBr 1.5 I 1.5 NCs not only act as additional light harvesters, but their chemical grafting onto the P3HT NRs improves the charge transport by creating better charge percolation pathways. The higher crystallinity of the P3HT NRs than P3HT also helps in reducing the trap states.
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