Sustainable Energy & Fuels最新文献

Triboelectric nanogenerators (TENGs), as the emerging ambient energy harvesting technology, can effectively convert the low-frequency and chaotic mechanical energy in the environment into electrical energy and have a unique advantage of power supply for micro-nano electronic devices, especially outdoors. Herein, we propose a single-electrode mode triboelectric nanogenerator (G-TENG) based on natural leaves as the friction layer and electrolytes inside the leaves as the electrode layer, which realizes the possibility of quickly generating energy by tapping the leaves in the field without external power supply. Experiments have shown that the electricity generated by tapping on a leaf can light up 225 white LED lights. In addition, an improved portable energy management circuit suitable for G-TENG has been further established to achieve fast charging of capacitors and meet the continuous power supply of electronic devices such as timers and temperature and humidity meters. We believe that this work has great potential for application in the field of outdoor self-power supply.

The global demand for renewable energy sources has intensified the quest for innovative and inexpensive solar cell technologies. Employing thin crystalline silicon (c-Si) is of great interest in these advancements. Herein, the integration of organic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and nanostructured thin-flexible Si wafers (∼50 μm) is investigated to harness their synergies in fabricating mechanically flexible hybrid heterojunction solar cells (HHSCs). Flexible Si wafers were prepared through alkali etching, followed by incorporation of silicon nanowires (SiNW) on one side of the thin wafers using a single-step silver (Ag)-assisted chemical etching (Ag-ACE) process at room temperature. The SiNW-incorporated flexible solar cells demonstrated an impressive power conversion efficiency (PCE: 9.0%) even with the simple design owing to enhanced light absorption in a broad spectral range. It is found that the SiNW length and polymer layer thickness play a critical role in defining the trade-off among the optoelectronic, junction and solar cell parameters. The SiNW with a 170 ± 20 nm length and PEDOT:PSS with a 100 ± 10 nm layer is the optimal combination for the best solar cell parameters. The enhanced light trapping and charge generation rate are also confirmed by finite-difference time-domain (FDTD) simulation. The detailed analysis of light trapping, junction properties, surface passivation, device performance parameters and their co-relation are discussed. Our study demonstrates the SiNW-incorporated flexible and efficient PEDOT:PSS/n-Si HHSCs, which can not only lead to the advancement of low-cost photovoltaics but also offer potential for diverse applications, from portable electronics to wearable technology.

A facile fast synthetic route is designed to prepare a versatile nano-electrocatalyst AgBi₃S₅ (ABS) for the generation of green fuel, H₂, via water electrolysis. The XRD pattern confirms the major formation of monoclinic phase AgBi₃S₅ (ABS) along with binary phase Ag₂S (AS) and Bi₂S₃ (BS). Another variant CuBiS₂(CBS) nanoparticle is synthesized to compare the electrochemical result with the unique sustainable as-synthesized nanoparticles of the ABS compound. Microscopy (HR-TEM) and spectroscopy (FTIR) studies provide confirmational evidence of the syntheses of ABS, AS, BS, and CBS, respectively, while an XPS study confirms the presence of Ag, Bi, and S in ABS. From the electrochemical analysis, it is evident that ABS shows a lower overpotential value of 47 mV compared to those of other variants (AS – 93 mV, BS – 191 mV, CBS – 603 mV) and lower Tafel slope values (mV dec⁻¹) (75.99) than the others (AS – 101.54, BS – 120.29, CBS – 265.2), which are key aspects in analyzing the catalytic activity performance of the catalyst. It is also proved that the rate-determining step of the reaction proceeds through the Volmer–Heyrovsky step. A lower EIS value of 9.84 Ω with a higher active surface area value of 0.092 cm² for ABS indicate superior and effective electron charge transfer kinetics on the electrode–electrolyte interface and elevated activity compared to the other electrocatalysts (AS – 15.24 Ω and 0.035 cm², BS – 16.01 Ω and 0.014 cm², and CBS – 19 Ω and 0.005 cm²). On top of that, an acceleration degradation (AD) study before and after analysis performed at 100 mVs⁻¹ for 500 cycles in acidic solution discloses the fact when comparing the two LSV curves there is a small hike (8 mV at 10 mA cm⁻²), suggesting higher stability and low catalyst degradation for ABS. Chronoamperometric studies with a fixed applied potential of −0.065 V vs. RHE also reveal that the catalyst (ABS) shows retention of activity after a 72 hour long-term process in a cathodic environment.

Alkaline water electrolysis is a mature method to produce green hydrogen; however, it suffers from significantly high cost as high overpotentials are required for the oxygen evolution reaction (OER). However, the OER could be avoided altogether by replacing it with kinetically favorable oxidation of abundantly available feedstock molecules at a significantly low potential to value-added product(s) together with green hydrogen generation. This is a potential method to address the high cost of green hydrogen production while converting waste to wealth. Herein, we report green, template-free hydrothermal synthesis of an electrochemically active NiCoMn mixed oxide (NCMO) electrocatalyst with multiple sites, porous structure, large surface area, and nanoneedle (NN) morphology deposited directly over Ni foam (NF). Sustainable electrocatalytic performance was demonstrated for 120 h in 0.2 M alkaline glycerol using chronoamperometry and chronopotentiometry. Highly selective formate production demonstrated an exclusive C–C cleavage with the present catalyst system. Oxides of individual metal-ions (Ni, Co, and Mn) and their bimetallic combination (NiCo, NiMn, and CoMn) exhibited lower activity and product selectivity than the trimetallic NCMO electrocatalyst. The membrane-free two-electrode electrolyzer setup with NCMO/NF at both the anode and cathode (NCMO/NF‖NCMO/NF) requires 1.63 V to accomplish 100 mA cm⁻² with 0.2 M glycerol, which is 296 mV less than that of 1 M KOH solution. High faradaic efficiency was observed for hydrogen (98%) with highly selective formate (90%) production. Electrocatalytic formate generation from an alkaline glycerol solution with NCMO is an energy-efficient and promising approach that also supplies carbon-negative green H₂.

The development of visible-light-active photocatalysts with high performance has been regarded as a promising way to address environmental wastewater issues. In this work, a highly efficient g-C₃N₄/CdS/TiO₂ ternary Z-type heterojunction photocatalyst with a hollow structure has been fabricated using a step-by-step self-assembly strategy, which demonstrates excellent photocatalytic performance under visible light and removes various water-soluble organic pollutants effectively. The photocatalytic degradation efficiency of 20-g-C₃N₄/CdS/TiO₂-10 against rhodamine B (RhB) is found to be 29.8 times higher than that of the pristine g-C₃N₄ within 90 minutes of visible light irradiation attributed to the active species of ˙O²⁻ and h⁺. Liquid chromatography mass spectrometry results suggest that the degradation pathway of RhB involves main steps such as N-de-ethylation, chromophore cleavage, ring opening, and mineralization. A series of characterization analyses, combined with the observed enhanced photocatalytic performance, indicate that the g-C₃N₄/CdS/TiO₂ ternary heterojunction benefits from the rapid transport and separation of photogenerated carriers facilitated by the formation of a heterointerface. Furthermore, the g-C₃N₄/CdS/TiO₂ ternary heterojunction exhibits favorable stability, with 88.1% degradation efficiency after five cycles of degradation experiments. This work provides novel insights into the preparation and application of ternary heterojunctions with superior photocatalytic performance for eliminating organic pollutants from wastewater.

This paper presents a theoretical analysis and simulation study on the heat transfer characteristics of heat exchange surfaces and flow channels under negative pressure. A theoretical analysis model of the air side in the heat transfer channel is established, and the dynamic and steady-state characteristics of the flow and thermal boundary layer inside the channel are derived as functions of environmental pressure variations. A CFD analysis is employed to establish a simulation model for the heat transfer process, and this model is used to simulate the field synergy of the finned tube heat exchanger under low-pressure conditions. The research results indicate that the heat transfer performance of the heat exchanger under negative pressure significantly deteriorates compared to atmospheric conditions. As the ambient pressure decreases from atmospheric pressure to −40 kPa, the heat transfer coefficient on the air side of the heat exchanger decreases by 30% to 47.7%. However, the pressure drop increases by 34.7% to 144.2%. This is closely related to changes in the properties of the cooling medium, the drastic variation of the boundary layer, and the alteration in the synergy between velocity and temperature fields in the low-pressure environment. Under the same boundary conditions such as velocity and temperature, the field synergy between the air-side velocity and temperature fields of the finned tube is higher under low pressure than under atmospheric pressure, which is attributed to the thickness variation of the flow boundary layer and thermal boundary layer caused by the decrease in environmental pressure. In addition, the attenuation of latent heat performance is mainly related to the mass transfer process and the drastic change of the concentration boundary layer under a low pressure environment.

Enhancing the Zeolite Socony Mobil-5 (ZSM-5) catalytic hydrocracking performance has been of interest in petrochemical processes. The synthesis of bifunctional Ni/Mo-impregnated ZSM-5 catalysts for catalytic hydrocracking of heavy distillate fractions of petroleum with a raw material of Badau Belitung kaolin was conducted as an effort to create more effective, affordable, and environmentally friendly catalysts. Based on the catalytic performance test results, Ni/Mo ZSM-5 has a good ability as a catalyst for catalytic hydrocracking of petroleum, producing medium and light distillate fractions. The catalytic hydrocracking of heavy petroleum distillates was performed under operating conditions of a final temperature of 425 °C and a maximum operating pressure of 60 bar (6 MPa), resulting in two optimum synthesis formulae, namely formula A and formula B. The Ni/Mo ZSM-5 formula A and formula B catalysts are capable of converting the heavy distillate of petroleum into medium and light fractions of 92.47% and 92.06% by mass, respectively. Commercial Ni/Mo γ-alumina and commercial Ni/Mo ZSM-5 catalysts were chosen as comparisons, yielding lower performance under the same operating conditions, with conversions of 70.40% and 87.19% by mass, respectively.

The quest for developing heterogeneous catalysts to synthesize cyclic carbonates from epoxides and carbon dioxide (CO₂) has attracted the attention of scientists in the past decade. Particularly, it is challenging to prepare cyclic carbonates using CO₂ under atmospheric pressure without the use of metal ions, additives, solvents, and halide ion-containing cocatalysts. This work reports the development of a metal- and halide-free porous organic polymer (POP) catalyst for the CO₂ fixation reaction. The POP synthesised from terephthaldehyde and 2,4,6-triaminopyrimidine possesses various functional groups (–NH₂, –NH, pyridine-N, etc.) that are known to activate epoxides and CO₂. The as-prepared POP displays excellent catalytic activity in the conversion of different epoxides to their corresponding cyclic carbonates with significant quantitative yields and selectivity. Additionally, the catalyst displays good recyclability without any noteworthy loss of catalytic activity and structural integrity, signifying its heterogeneous nature.