Hydrate-based CO2/H2 separation provides an attractive route for pre-combustion CO2 capture with simultaneous H2 enrichment; however, its practical application remains constrained by sluggish hydrate formation and the limited understanding of environmentally benign kinetic promoters under CO2-rich fuel-gas conditions. In this study, we first examine the effect of the thermodynamic promoter tetrahydrofuran (THF) on hydrate formation from a CO2/H2 (60:40) mixture at 3.0 MPa and establish 5.56 mol % as the optimum concentration under the investigated experimental conditions. Increasing the THF concentration from 3.0 to 5.56 mol % increases gas uptake from 15.98 to 20.93 mmol/mol H2O and reduces T 90 from 74.5 to 18.5 min over 280.2-283.2 K. The optimized THF system is subsequently coupled with three hydrophobic amino acids (0.5 wt % l-Methionine, l-Leucine, and l-Tryptophan) to promote hydrate growth. Their effects are evaluated experimentally and further interpreted using a chemical-potential-driven kinetic model for structure II (sII) hydrate formation. The amino acids influence hydrate growth in a molecule-dependent manner, with l-Leucine and l-Methionine exhibiting the most favourable kinetic and hydrate-yield characteristics. Despite the enhanced formation behaviour, the preferential separation of CO2 is retained: gas chromatographic analysis shows 92.7-94.7% CO2 in the hydrate phase, while the residual vapour is enriched to as much as 59.3% H2. By combining THF and amino-acid-assisted promotion, and chemical-potential-based kinetic modelling, this study links molecular-level promotion with macroscopic hydrate growth and phase selectivity in a CO2-rich CO2/H2 system. The findings provide a basis for developing hydrate-based separation processes that couple CO2 capture with H2 enrichment.
The development of earth-abundant co-catalysts that enhance TiO2-driven hydrogen evolution remains crucial for sustainable photocatalytic H2 production. This work investigates Mo addition as a compositional strategy to tune the co-catalytic functionality of Fe3S4 for photocatalytic HER over TiO2. A series of x%Mo-Fe3S4 (x = 0, 1, 2, 5, and 7.5) materials was prepared and evaluated using both conventional solvothermal synthesis (18 h) and a microwave-assisted non-aqueous sol-gel route requiring 30 min. When combined with anatase TiO2 as a model photocatalyst at a fixed co-catalyst loading (5 wt %), Mo addition markedly improved the performance of the Fe3S4 co-catalyst. Structural, surface, and optical characterizations indicate that Mo addition modifies the sulfides, in parallel with the observed improvement in co-catalytic hydrogen evolution reaction (HER) performance. Under UV-Vis irradiation (300 W Xe lamp), the best solvothermal composite (5%Mo-Fe3S4@TiO2) reached similar to 30 mu mol H2 h-1 after 3 h irradiation, corresponding to 25 times the rate of bare TiO2. For the microwave-derived series, the 7.5%Mo-Fe3S4@TiO2 composite delivered similar to 29 mu mol H2 h-1 after 3 h, corresponding to 24 times higher than bare TiO2, and 5 times higher than undoped Fe3S4@TiO2. Overall, Mo-doped Fe3S4 emerges as an earth-abundant, non-noble metal co-catalyst platform that significantly improves photocatalytic HER with TiO2 while maintaining performance under a time-efficient synthesis protocol.
Crystal facet engineering and Bi incorporation are effective strategies to enhance photocatalytic CO2 reduction, yet their synergistic effects in ZnIn2S4 remain underexplored. Herein, Bi-modified ZnIn2S4 (Bi-ZIS) with a preferentially exposed (006) plane and enriched sulfur vacancies (VS) was constructed via a combined crystal facet engineering and Bi-doping strategy. The optimized 5% Bi-ZIS exhibited the highest photocatalytic performance, producing CO and CH4 yields of 242 and 45 mu mol g-1 under visible-light irradiation for 3 h. Comprehensive characterizations revealed that the exposed (006) plane, sulfur vacancies, and Bi nanoparticles collectively promoted light harvesting, charge separation, and CO2 activation. In situ DRIFTS confirmed the presence of key intermediates (*COOH, CHO*, CH3O*), and DFT calculations verified electronic-structure modulation induced by Bi doping. This work provides an efficient strategy for rational design of ZnIn2S4-based photocatalysts via synergistic crystal facet and defect engineering for solar-driven CO2 conversion.
Conventional lithium-ion batteries (LIBs) require metallic current collectors such as copper for anodes and aluminum for cathodes, adding significant weight without contributing to the capacity. This is especially problematic for Si-dominant anodes, with mass loadings lower than 2 mg cm-2. Here, copper is replaced with lightweight, non-woven carbon nanotube fabrics (CNTfs) combined with high-capacity Si/PPAN active material to form a self-standing composite anode. This lightweight electrode delivers a capacity of 1000 mAh g-1 (normalized with respect to the total Si/PPAN/CNTf anode weight) for over 700 cycles at a current density of 1 A g-1 and can potentially boost the cell-level energy density by similar to 25% when paired with commercial cathodes. Cross-sectional SEM-EDX imaging and peel tests confirm excellent interfacial contact between the Si/PPAN layer and CNTf current collector. Furthermore, the effects of increasing CNTf thickness reveal more evident SEI formation in the CNTf layer, lowering the first-cycle Coulombic efficiency. These findings demonstrate the potential of using CNTfs in high-energy LIBs, while also reducing emissions associated with metal manufacturing.
Abstract Perovskite solar cells are currently well known for both their outstanding advantages and their main drawback: rapid degradation when exposed to external agents. In particular, the sensitivity of these devices to ultraviolet (UV) radiation has been widely reported, where the underlying degradation mechanisms in metal oxide-free p–i–n architectures remain insufficiently understood. In this work, we systematically investigate the impact of UV irradiation (385 nm) on metal oxide-free p–i–n PSCs under inert atmosphere, combining optical simulations, morphological characterization (SEM and AFM), current-voltage analysis, scan-rate-dependent measurements, and impedance spectroscopy. Optical modeling reveals that UV photons are absorbed within the first few tens of nanometers of the perovskite layer, near the hole transport layer (HTL)/perovskite interface. Consistently, SEM and AFM analyses show significant surface restructuring after UV exposure, including grain coarsening and increased roughness. Electrically, degradation is dominated by a severe loss of short-circuit current density, accompanied by a progressive reduction in fill factor, while the open-circuit voltage remains comparatively stable. Detailed DC and AC analyses demonstrate that these effects originate from a coupled ionic-electronic degradation mechanism. UV exposure promotes the accumulation of mobile ions, leading to screening of the internal electric field and impaired charge extraction, while simultaneously generating deep trap states at or near the HTL/perovskite interface that enhance Shockley-Read-Hall recombination. Impedance spectroscopy further reveals increased ionic transport and the emergence of fast interfacial processes associated with trap-assisted recombination. These findings provide a comprehensive mechanistic framework for understanding UV-induced degradation in metal oxide-free p–i–n perovskite solar cells and highlight the critical role of interfacial ion-trap interactions in limiting device stability, even under inert and encapsulated operating conditions.
