Modulating the Cu2O Photoelectrode/Electrolyte Interface with Bilayer Surfactant Simulating Cell Membranes for Boosting Photoelectrochemical CO2 Reduction.

The low solubility of CO2 molecules and the competition of the hydrogen evolution reaction (HER) in aqueous electrolytes pose significant challenges to the current photoelectrochemical (PEC) CO2 reduction reaction. In this study, inspired by the bilayer phospholipid molecular structure of cell membranes, we developed a Cu2O/Sn photocathode that was modified with the bilayer surfactant DHAB for achieving high CO2 permeability and suppressed HER. The Cu2O/Sn/DHAB photocathode stabilizes the *OCHO intermediate and facilitates the production of HCOOH. Our findings show that the Faradaic efficiency (FE) of HCOOH by the Cu2O/Sn/DHAB photoelectrode is 83.3%, significantly higher than that achieved with the Cu2O photoelectrode (FEHCOOH = 30.1%). Furthermore, the FEH2 produced by the Cu2O/Sn/DHAB photoelectrode is only 2.95% at -0.6 V vs RHE. The generation rate of HCOOH by the Cu2O/Sn/DHAB photoelectrode reaches 1.52 mmol·cm-2·h-1·L-1 at -0.7 V vs RHE. Our study provides a novel approach for the design of efficient photocathodes for CO2 reduction.

Hydrophobic surface efficiently boosting Cu2O nanowires photoelectrochemical CO2 reduction activity.

The limited mass transfer of CO2 and the competitive hydrogen evolution reaction (HER) during photoelectrochemical (PEC) CO2 reduction usually result in low CO2 reduction activity. Here, we constructed a Cu2O/Sn/PTFE photocathode with a hydrophobic surface based on Cu2O by physical vapor deposition and a dipping method. The CO faradaic efficiency (FE) increased from 34.5% (Cu2O) to 95.1% (Cu2O/Sn/PTFE) at -0.7 V vs. RHE, and the FEH2 decreased from 27.9% (Cu2O) to 3.8% (Cu2O/Sn/PTFE). The introduction of the hydrophobic layer enhances the local CO2 concentration on the electrode surface and effectively isolates H+ from the aqueous electrolyte, thereby enhancing the CO2 reduction activity.

Oriented CuWO4 Films for Improved Photoelectrochemical Water Splitting.

Hydrogen generation through photoelectrochemical (PEC) technology is one of the most appropriate ways for delivering sustainable fuel. Simultaneously, anisotropic properties will be exhibited by the materials with low crystal symmetry, allowing the tuning of the PEC properties by controlling the crystallographic orientation and exposed facets. Therefore, we synthesized copper tungstate films (CuWO4) with highly exposed (100) crystal facets by regulating anions in the precursor solution. According to experimental characterization and density functional theory calculations, the CuWO4 film with a high exposure ratio of the (100) crystal facet has promoted charge transport with trap-free mode and reduced recombination of electrons and holes. Meanwhile, the oxygen evolution reaction is promoted on the (100) facet because of the relatively low energy barrier. Compared to the CuWO4 with other mixed exposure facets, CuWO4 with a highly exposed (100) facet presents a twofold current density (0.38 mA/cm2) and one-fifteenth electron transit time (0.698 ms) and also has great stability (more than 6 h). These results provide an easy way to enhance the PEC performance by modulating the exposure facets of the film electrode.

Microwave hydrothermal renovating and reassembling spent lithium cobalt oxide for lithium-ion battery.

With the growing number of lithium-ion batteries (LIBs) that are consumed by worldwide people, recycling is necessary for addressing environmental problems and alleviating energy crisis. Especially, it is meaningful to regenerate LIBs from spent batteries. In this paper, the microwave hydrothermal method is used to replenish lithium, assemble particles and optimize the crystal structure of the spent lithium cobalt oxide. The microwave hydrothermal process can shorten the reaction time, improve the internal structure, and uniformize the particle size distribution of lithium cobalt oxide. It helps to construct a regenerated lithium cobalt oxide (LiCoO2) battery with high-capacity and high-rate properties (141.7 mAh g-1 at 5C). The cycle retention rate is 94.5% after 100 cycles, which is far exceeding the original lithium cobalt oxide (89.7%) and LiCoO2 regenerated by normal hydrothermal method (88.3%). This work demonstrates the feasibility to get lithium cobalt oxide batteries with good structural stability from spent lithium cobalt oxide batteries.

Localized Self-Growth of Reconfigurable Architectures Induced by a Femtosecond Laser on a Shape-Memory Polymer.

Architectures of natural organisms especially plants largely determine their response to varying external conditions. Nature-inspired shape transformation of artificial materials has motivated academic research for decades due to wide applications in smart textiles, actuators, soft robotics, and drug delivery. A "self-growth" method of controlling femtosecond laser scanning on the surface of a prestretched shape-memory polymer to realize microscale localized reconfigurable architectures transformation is introduced. It is discovered that microstructures can grow out of the original surface by intentional control of localized laser heating and ablation, and resultant structures can be further tuned by adopting an asymmetric laser scanning strategy. A distinguished paradigm of reconfigurable architectures is demonstrated by combining the flexible and programmable laser technique with a smart shape-memory polymer. Proof-of-concept experiments are performed respectively in information encryption/decryption, and microtarget capturing/release. The findings reveal new capacities of architectures with smart surfaces in various interdisciplinary fields including anti-counterfeiting, microstructure printing, and ultrasensitive detection.