Abstract
Recently developed solid-state catalysts can mediate carbon dioxide (CO
2
) electroreduction to valuable products at high rates and selectivities. However, under commercially relevant ...current densities of > 200 milliamperes per square centimeter (mA cm
−2
), catalysts often undergo particle agglomeration, active-phase change, and/or element dissolution, making the long-term operational stability a considerable challenge. Here we report an indium sulfide catalyst that is stabilized by adding zinc in the structure and shows dramatically improved stability. The obtained ZnIn
2
S
4
catalyst can reduce CO
2
to formate with 99.3% Faradaic efficiency at 300 mA cm
−2
over 60 h of continuous operation without decay. By contrast, similarly synthesized indium sulfide without zinc participation deteriorates quickly under the same conditions. Combining experimental and theoretical studies, we unveil that the introduction of zinc largely enhances the covalency of In-S bonds, which “locks” sulfur—a catalytic site that can activate H
2
O to react with CO
2
, yielding HCOO* intermediates—from being dissolved during high-rate electrolysis.
Selective and efficient catalytic conversion of carbon dioxide (CO2) into value-added fuels and feedstocks provides an ideal avenue to high-density renewable energy storage. An impediment to enabling ...deep CO2 reduction to oxygenates and hydrocarbons (e.g., C2+ compounds) is the difficulty of coupling carbon–carbon bonds efficiently. Copper in the +1 oxidation state has been thought to be active for catalyzing C2+ formation, whereas it is prone to being reduced to Cu0 at cathodic potentials. Here we report that catalysts with nanocavities can confine carbon intermediates formed in situ, which in turn covers the local catalyst surface and thereby stabilizes Cu+ species. Experimental measurements on multihollow cuprous oxide catalyst exhibit a C2+ Faradaic efficiency of 75.2 ± 2.7% at a C2+ partial current density of 267 ± 13 mA cm–2 and a large C2+-to-C1 ratio of ∼7.2. Operando Raman spectra, in conjunction with X-ray absorption studies, confirm that Cu+ species in the as-designed catalyst are well retained during CO2 reduction, which leads to the marked C2+ selectivity at a large conversion rate.
Although the Turing structures, or stationary reaction‐diffusion patterns, have received increasing attention in biology and chemistry, making such unusual patterns on inorganic solids is ...fundamentally challenging. We report a simple cation exchange approach to produce Turing‐type Ag2Se on CoSe2 nanobelts relied on diffusion‐driven instability. The resultant Turing‐type Ag2Se‐CoSe2 material is highly effective to catalyze the oxygen evolution reaction (OER) in alkaline electrolytes with an 84.5 % anodic energy efficiency. Electrochemical measurements show that the intrinsic OER activity correlates linearly with the length of Ag2Se‐CoSe2 interfaces, determining that such Turing‐type interfaces are more active sites for OER. Combing X‐ray absorption and computational simulations, we ascribe the excellent OER performance to the optimized adsorption energies for critical oxygen‐containing intermediates at the unconventional interfaces.
A novel Turing‐type Ag2Se‐CoSe2 structure has been synthesized, which possesses rich Ag2Se‐CoSe2 interfaces, exhibiting a 221 mV overpotential at a current density of 10 mA cm−2 in 0.1 M KOH electrolyte with a high anodic energy efficiency of 84.5 %.
Copper is currently the material with the most promise as catalyst to drive carbon dioxide (CO2) electroreduction to produce value-added multicarbon (C2+) compounds. However, a copper catalyst on a ...carbon-based gas diffusion layer electrode often has poor stabilityespecially when performing at high current densitiesowing to electrolyte flooding caused by the hydrophobicity decrease of the gas diffusion layer during operation. Here, we report a bioinspired copper catalyst on a gas diffusion layer that mimics the unique hierarchical structuring of Setaria’s hydrophobic leaves. This hierarchical copper structure endows the CO2 reduction electrode with sufficient hydrophobicity to build a robust gas–liquid–solid triple-phase boundary, which can not only trap more CO2 close to the active copper surface but also effectively resist electrolyte flooding even under high-rate operation. We consequently achieved a high C2+ production rate of 255 ± 5.7 mA cm–2 with a 64 ± 1.4% faradaic efficiency, as well as outstanding operational stability at 300 mA cm–2 over 45 h in a flow reactor, largely outperforming its wettable copper counterparts.
Detailed particle breakage adjacent to a pile has great influence on the settlement and bearing capacity of a pile foundation. Before the pile test, coral sand was divided into different grain-size ...groups and dyed in different colors, then mixed as the ground soil. After pile penetration, the sand around the pile was divided into many zones and sampled. Grains in different colors in each size range of each sample were discerned quantitatively. Results show that the settlement curve dropped fast and the skin friction of pile was small due to the obvious particle breakage. In each zone, the actual particle breakage in each size range was different from the change in relative mass percentage, and the lost of angular edges is the dominant type of particle breakage under the bottom pressure of pile. The index
B
ag
, excluding the interference effect of size overlap between fragments and unbroken grains in each size range, was slightly larger than
B
g
for most zones around the pile. The breakage-zone was limited to 1.5 times of the pile diameter at the radial direction and 2.5 times at the depth direction, which is much deeper than that in silica sand. Particle breakage at some distance from pile bottom is larger than that at the very bottom of the pile due to the shearing effect in the sand. Detailed particle breakage around the pile is useful in studying the interaction between the pile and crushable granular soil.
The electrosynthesis of valuable multicarbon chemicals using carbon dioxide (CO2) as a feedstock has substantially progressed recently but still faces considerable challenges. A major difficulty ...lines in the sluggish kinetics of forming carbon–carbon (C–C) bonds, especially in neutral media. We report here that oxide-derived copper crystals enclosed by six {100} and eight {111} facets can reduce CO2 to multicarbon products with a high Faradaic efficiency of 74.9 ± 1.7% at a commercially relevant current density of 300 mA cm–2 in 1 M KHCO3 (pH ∼ 8.4). By combining the experimental and computational studies, we uncovered that Cu(100)/Cu(111) interfaces offer a favorable local electronic structure that enhances *CO adsorption and lowers C–C coupling activation energy barriers, performing superior to Cu(100) and Cu(111) surfaces, respectively. On this catalyst, no obvious degradation was observed at 300 mA cm–2 over 50 h of continuous operation.
In this article, enhancement-mode thin-film transistors (TFTs) with atomic layer deposition (ALD)-derived ultrathin (<inline-formula> <tex-math notation="LaTeX">\approx</tex-math> </inline-formula>3 ...nm) amorphous indium-zinc oxide (a-IZO) channel were demonstrated. Our devices showed improved device characteristics as benchmarked with thicker IZO thin-film channels. The ALD-deposited IZO channel TFT with an In/Zn ratio of <inline-formula> <tex-math notation="LaTeX">\approx</tex-math> </inline-formula>6:4 exhibited a high field-effect channel mobility (<inline-formula> <tex-math notation="LaTeX">\mu_{\text{FE}}\text{)}</tex-math> </inline-formula> of 53.6 cm<inline-formula> <tex-math notation="LaTeX">^{\text{2}}</tex-math> </inline-formula>/V-s, a threshold voltage (<inline-formula> <tex-math notation="LaTeX">\textit{V}_{\text{th}}\text{)}</tex-math> </inline-formula> of 0.28 V, a low subthreshold gate swing of 74 mV/decade, an <inline-formula> <tex-math notation="LaTeX">I_{\biosc{on}}/I_{\biosc{off}}</tex-math> </inline-formula> ratio of <inline-formula> <tex-math notation="LaTeX">></tex-math> </inline-formula>10<inline-formula> <tex-math notation="LaTeX">^{\text{9}}</tex-math> </inline-formula>, and a contact resistance of 0.18 k<inline-formula> <tex-math notation="LaTeX">\Omega </tex-math> </inline-formula>-<inline-formula> <tex-math notation="LaTeX">\mu </tex-math> </inline-formula>m after 300 <inline-formula> <tex-math notation="LaTeX">{^{\circ}}</tex-math> </inline-formula>C anneal in oxygen atmosphere. Physical analysis, including X-ray and ultraviolet (UV) photoelectron spectra of IZO films, was conducted to understand the mechanisms of enhancement in electrical performance after annealing. The threshold voltages of the TFT also exhibited high stability (<inline-formula> <tex-math notation="LaTeX">\Delta\textit{V}_{\text{th, PBS}}</tex-math> </inline-formula> <inline-formula> <tex-math notation="LaTeX"><</tex-math> </inline-formula> 16 mV and <inline-formula> <tex-math notation="LaTeX">\Delta\textit{V}_{\text{th, NBS}}</tex-math> </inline-formula> <inline-formula> <tex-math notation="LaTeX"><</tex-math> </inline-formula> 12 mV) after positive bias stress (PBS) and negative bias stress (NBS) test for 3600 s. To the best of our knowledge, we reported the TFT with thinnest IZO ternary oxide semiconductor (OS) channel exhibiting superior channel mobility and subthreshold characteristics.
Light management holds great promise of realizing high‐performance perovskite solar cells by improving the sunlight absorption with lower recombination current and thus higher power conversion ...efficiency (PCE). Here, a convenient and scalable light trapping scheme is demonstrated by incorporating bioinspired moth‐eye nanostructures into the metal back electrode via soft imprinting technique to enhance the light harvesting in organic–inorganic lead halide perovskite solar cells. Compared to the flat reference cell with a methylammonium lead halide perovskite (CH3NH3PbI3−xClx) absorber, 14.3% of short‐circuit current improvement is achieved for the patterned devices with moth‐eye nanostructures, yielding an increased PCE up to 16.31% without sacrificing the open‐circuit voltage and fill factor. The experimental and theoretical characterizations verify that the cell performance enhancement is mainly ascribed by the broadband polarization‐insensitive light scattering and surface plasmonic effects due to the patterned metal back electrode. It is noteworthy that this light trapping strategy is fully compatible with solution‐processed perovskite solar cells and opens up many opportunities toward the future photovoltaic applications.
A convenient and scalable light trapping scheme is demonstrated to enhance the light harvesting in organic–inorganic lead halide perovskite solar cells, which is realized by incorporating bioinspired moth‐eye nanostructures into the metal back electrode via soft imprinting technique. The efficiency is enhanced to 16.3% due to self‐enhanced absorption by broadband polarization‐insensitive light scattering and surface plasmonic effect.
Carbon–carbon coupling electrochemistry on a conventional copper (Cu) catalyst still undergoes low selectivity among many different multicarbon (C2+) chemicals, posing a grand challenge to achieve a ...single C2+ product. Here, we demonstrate a laser irradiation synthesis of a gerhardtite mineral, Cu2(OH)3NO3, as a catalyst precursor to make a Cu catalyst with abundant stacking faults under reducing conditions. Such structural perturbation modulates electronic microenvironments of Cu, leading to improved d-electron back-donation to the antibonding orbital of *CO intermediates and thus strengthening *CO adsorption. With increased *CO coverage on the defect-rich Cu, we report an acetate selectivity of 56 ± 2% (compared to 31 ± 1% for conventional Cu) and a partial current density of 222 ± 7 mA per square centimeter in CO electroreduction. When run at 400 mA per square centimeter for 40 h in a flow reactor, this catalyst produces 68.3 mmol of acetate throughout. This work highlights the value of a Cu-containing mineral phase in accessing suitable structures for improved selectivity to a single desired C2+ product.
Hierarchical architecture is of vital importance in soft materials. Focal conic domains (FCDs) of smectic liquid crystals, characterized by an ordered lamellar structure, attract intensive attention. ...Simultaneously tailoring the geometry and clustering characteristics of FCDs remains a challenge. Here, the 3D smectic layer origami via a 2D preprogrammed photoalignment film is accomplished. Full control of hierarchical superstructures is demonstrated, including the domain size, shape, and orientation, and the lattice symmetry of fragmented toric FCDs. The unique symmetry breaking of resultant superstructures combined with the optical anisotropy of the liquid crystals induces an intriguing polarization‐dependent diffraction. This work broadens the scientific understanding of self‐assembled soft materials and may inspire new opportunities for advanced functional materials and devices.
Full control of 3D smectic layer origami is realized by a 2D preprogrammed photoalignment film, including both the geometry and clustering characteristics of fragmented focal conic domains (FCDs). The unique symmetry breaking of FCDs combined with the optical anisotropy of liquid crystals induces a metasurface‐like polarization‐dependent diffraction. This work broadens the scientific understanding and inspires new opportunities to soft materials.
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