Green Energy & Environment最新文献

Fabricating non-noble metal-based carbon air electrodes with highly efficient bifunctionality is big challenge owing to the sluggish kinetics of oxygen reduction/evolution reaction (ORR/OER). The efficient cathode catalyst is urgently needed to further improve the performance of rechargeable zinc-air batteries. Herein, an activation-doping assisted interface modification strategy is demonstrated based on freestanding integrated carbon composite (CoNiLDH@NPC) composed of wood-based N and P doped active carbon (NPC) and CoNi layer double hydroxides (CoNiLDH). In the light of its large specific surface area and unique defective structure, CoNiLDH@NPC with strong interface-coupling effect in 2D-3D micro-nanostructure exhibits outstanding bifunctionality. Such carbon composites show half-wave potential of 0.85 V for ORR, overpotential of 320 mV with current density of 10 mA cm^-2 for OER, and ultra-low gap of 0.70 V. Furthermore, highly-ordered open channels of wood provide enormous space to form abundant triple-phase boundary for accelerating the catalytic process. Consequently, Zinc-air batteries using CoNiLDH@NPC show high power density (aqueous: 263 mW cm^-2, quasi-solid-state: 65.8 mW cm^-2) and long-term stability (aqueous: 500 h, quasi-solid-state: 120 h). This integrated protocol opens a new avenue for the rational design of efficient freestanding air electrode from biomass resources.

RuO₂ has been considered a potential alternative to commercial IrO₂ for the oxygen evolution reaction (OER) due to its superior intrinsic activity. However, its inherent structure dissolution in acidic environments restricts its commercial applications. In this study, we report a novel Pd-doped ruthenium oxide (Pd-RuO₂) nanosheet catalyst that exhibits improved activity and stability through a synergistic effect of Pd modulation of Ru electronic structure and the two-dimensional structure. The catalyst exhibits excellent performance, achieving an overpotential of only 204 mV at a current density of 10 mA cm^-2. Impressively, after undergoing 8000 cycles of cyclic voltammetry testing, the overpotential merely decreased by 5 mV. The PEM electrolyzer with Pd_0.08Ru_0.92O₂ as an anode catalyst survived an almost 130 h operation at 200 mA cm^-2. To elucidate the underlying mechanisms responsible for the enhanced stability, we conducted an X-ray photoelectron spectroscopy (XPS) analysis, which reveals that the electron transfer from Pd to Ru effectively circumvents the over-oxidation of Ru, thus playing a crucial role in enhancing the catalyst's stability. Furthermore, density functional theory (DFT) calculations provide compelling evidence that the introduction of Pd into RuO₂ effectively modulates electron correlations and facilitates the electron transfer from Pd to Ru, thereby preventing the over-oxidation of Ru. Additionally, the application of the two-dimensional structure effectively inhibited the aggregation and growth of nanoparticles, further bolstering the structural integrity of the catalyst.

Charge separation is critical for achieving efficient solar-to-hydrogen conversion, whereas piezoelectric-enhanced photoelectrochemical (PEC) systems can effectively modulate band bending and charge migration. Herein, we design an n-TiO₂/BaTiO₃/p-TiO₂ (TBTm) heterojunction in which the piezoelectric BaTiO₃ layer is sandwiched between n-TiO₂ and p-TiO₂. The built-in electric field of TBTm can provide a strong driving force to accelerate carrier separation and prolong carrier lifetime. Consequently, the TBT3 achieves a prominent photocurrent density, as high as 2.13 mA∙cm^-2 at 1.23 V versus reversible hydrogen electrode (RHE), which is 2.4- and 1.5-times higher than TiO₂ and TiO₂-BaTiO₃ heterojunction, respectively. Driven by mechanical deformation, the induced dipole polarization can further regulate built-in electric fields, and the piezoelectric photocurrent density of TBT3-800 is 2.84 times higher than TiO₂ at 1.23 V vs. RHE due to the construction of piezoelectric-heterostructures. This work provides a piezoelectric polarization strategy for modulating the built-in electric field of heterojunction for PEC system.

For decades micoorganisms have been engineered for the utilization of lignocellulose-based second-generation (2G) feedstocks, but with the concerns of increased levels of atmospheric CO₂ causing global warming there is an emergent need to transition from the utilization of 2G feedstocks to third-generation (3G) feedstocks such as CO₂ and its derivatives. Here, we established a yeast platform that is capable of simultaneously converting 2G and 3G feedstocks into bulk and value-added chemicals. We demonstrated that by adopting 3G substrates such as CO₂ and formate, the conversion of 2G feedstocks could be substantially improved. Specifically, formate could provide reducing power and energy for xylose conversion into valuable chemicals. Simultaneously, it can form a concentrated CO₂ pool inside the cell, providing thermodynamically and kinetically favoured amounts of precursors for CO₂ fixation pathways, e.g. the Calvin–Benson–Bassham (CBB) cycle. Furthermore, we demonstrated that formate could directly be utilized as a carbon source by yeast to synthesize endogenous amino acids. The engineered strain achieved a one-carbon (C1) assimilation efficiency of 9.2%, which was the highest efficiency observed in the co-utilization of 2G and 3G feedstocks. We applied this strategy for productions of both bulk and value-added chemicals, including ethanol, free fatty acids (FFAs), and longifolene, resulting in yield enhancements of 18.4%, 49.0%, and ∼100%, respectively. The strategy demonstrated here for co-utilization of 2G and 3G feedstocks sheds lights on both basic and applied research for the up-coming establishment of 3G biorefineries.

Converting carbohydrates into 5-hydroxymethylfurfural (5-HMF) is an attractive and promising route for value-added utilization of agricultural and forestry biomass resource. As an important platform compound, 5-HMF possesses high active furan structure with hydroxymethyl and aldehyde group for production of various bio-chemicals and materials, meanwhile, which suffer from low stability and poor yield during the industrial biorefinery process. Hence, selective production of 5-HMF with high-yield and low-cost has attracted extensive attention from scientific and industrial researchers. This review sorted and described the latest advanced research on solvent and catalyst system, as well as energy field effect for production of 5-HMF with different feedstock in detail, emphatically discussing the solvent effect and its synergistic effect with other aspects. Besides, the future prospects and challenges for production of 5-HMF from carbohydrates were also presented, which provide a profound insight into industrial 5-HMF process with economic and environmental feature.