In catalysis science stability is as crucial as activity and selectivity. Understanding the degradation pathways occurring during operation and developing mitigation strategies will eventually improve catalyst design, thus facilitating the translation of basic science to technological applications. Herein, we reveal the unique and general degradation mechanism of metallic nanocatalysts during electrochemical CO2 reduction, exemplified by different sized copper nanocubes. We follow their morphological evolution during operation and correlate it with the electrocatalytic performance. In contrast with the most common coalescence and dissolution/precipitation mechanisms, we find a potential-driven nanoclustering to be the predominant degradation pathway. Grand-potential density functional theory calculations confirm the role of the negative potential applied to reduce CO2 as the main driving force for the clustering. This study offers a novel outlook on future investigations of stability and degradation reaction mechanisms of nanocatalysts in electrochemical CO2 reduction and, more generally, in electroreduction reactions.

Understanding the structural and compositional sensitivities of the electrochemical CO2 reduction reaction (CO2RR) is fundamentally important for developing highly efficient and selective electrocatalysts. Here, we use Ag/Cu nanocrystals to uncover the key role played by the Ag/Cu interface in promoting CO2RR. Nanodimers including the two constituent metals as segregated domains sharing a tunable interface are obtained by developing a seeded growth synthesis, wherein preformed Ag nanoparticles are used as nucleation seeds for the Cu domain. We find that the type of metal precursor and the strength of the reducing agent play a key role in achieving the desired chemical and structural control. We show that tandem catalysis and electronic effects, both enabled by the addition of Ag to Cu in the form of segregated nanodomain within the same catalyst, synergistically account for an enhancement in the Faradaic efficiency for C2H4 by 3.4-fold and in the partial current density for CO2 reduction by 2-fold compared with the pure Cu counterpart. The insights gained from this work may be beneficial for designing efficient multicomponent catalysts for electrochemical CO2 reduction.

We achieved improvement in performance and stability of PSCs by growing 2D perovskite layer on top of 3D perovskite films.

The single-layer graphene film, when incorporated with molecular-sized pores, is predicted to be the ultimate membrane. However, the major bottlenecks have been the crack-free transfer of large-area graphene on a porous support, and the incorporation of molecular-sized nanopores. Herein, we report a nanoporous-carbon-assisted transfer technique, yielding a relatively large area (1 mm2), crack-free, suspended graphene film. Gas-sieving (H2/CH4 selectivity up to 25) is observed from the intrinsic defects generated during the chemical-vapor deposition of graphene. Despite the ultralow porosity of 0.025%, an attractive H2 permeance (up to 4.1 × 10−7 mol m−2 s−1 Pa−1) is observed. Finally, we report ozone functionalization-based etching and pore-modification chemistry to etch hydrogen-selective pores, and to shrink the pore-size, improving H2 permeance (up to 300%) and H2/CH4 selectivity (up to 150%). Overall, the scalable transfer, etching, and functionalization methods developed herein are expected to bring nanoporous graphene membranes a step closer to reality.

Drinking water contamination with heavy metals, particularly lead, is a persistent problem worldwide with grave public health consequences. Existing purification methods often cannot address this problem quickly and economically. Here we report a cheap, water stable metal–organic framework/polymer composite, Fe-BTC/PDA, that exhibits rapid, selective removal of large quantities of heavy metals, such as Pb2+ and Hg2+, from real world water samples. In this work, Fe-BTC is treated with dopamine, which undergoes a spontaneous polymerization to polydopamine (PDA) within its pores via the Fe3+ open metal sites. The PDA, pinned on the internal MOF surface, gains extrinsic porosity, resulting in a composite that binds up to 1634 mg of Hg2+ and 394 mg of Pb2+ per gram of composite and removes more than 99.8% of these ions from a 1 ppm solution, yielding drinkable levels in seconds. Further, the composite properties are well-maintained in river and seawater samples spiked with only trace amounts of lead, illustrating unprecedented selectivity. Remarkably, no significant uptake of competing metal ions is observed even when interferents, such as Na+, are present at concentrations up to 14 000 times that of Pb2+. The material is further shown to be resistant to fouling when tested in high concentrations of common organic interferents, like humic acid, and is fully regenerable over many cycles.

Herein, the assembly of CsPbBr QD/AlO inorganic nanocomposites, by using atomic layer deposition (ALD) for the growth of the amorphous alumina matrix (AlO ), is described as a novel protection scheme for such QDs. The nucleation and growth of AlO on the QD surface was thoroughly investigated by miscellaneous techniques, which highlighted the importance of the interaction between the ALD precursors and the QD surface to uniformly coat the QDs while preserving the optoelectronic properties. These nanocomposites show exceptional stability towards exposure to air (for at least 45 days), irradiation under simulated solar spectrum conditions (for at least 8 h), and heat (up to 200 °C in air), and finally upon immersion in water. This method was extended to the assembly of CsPbBr I QD/AlO and CsPbI QD/AlO nanocomposites, which were more stable than the pristine QD films.

A new aliphatic fluorinated amphiphilic additive is added to CH3 NH3 PbI3 perovskite to tune the morphology and enhance the environmental stability without sacrificing the performance of the devices. Judicious screening of the perovskite precursor solution realizes a power conversion efficiency of 18.0% for mesoporous perovskite solar cells as a result of improved surface coverage. A slower degradation in ambient air is observed with this modified perovskite.

With the ever-increasing production of electronics, there is an ensuing need for gold extraction from sources other than virgin mines. Currently, there are no technologies reported to date that can effectively and selectively concentrate ultratrace amounts of gold from liquid sources. Here, we provide a blueprint for the design of several highly porous composites made up of a metal−organic framework (MOF) template and redox active, polymeric building blocks. One such composite, Fe-BTC/PpPDA, is shown to rapidly extract trace amounts of gold from several complex water mixtures that include wastewater, fresh water, ocean water, and solutions used to leach gold from electronic waste and sewage sludge ash. The material has an exceptional removal capacity, 934 mg gold/g of composite, and extracts gold from these complex mixtures at recordbreaking rates, in as little as 2 min. Further, due to the high cyclability, we demonstrate that the composite can effectively concentrate gold and yield purities of 23.9 K.