查看更多>>摘要：? 2022 Elsevier B.V.Self-catalyzed decomplexation of Cu-ethylene diamine tetraacetic acid complex (Cu-EDTA) and recovery of Cu without addition of extraneous transition metals were achieved in Ti3C2Tx MXene/peroxymonosulfate (Ti3C2Tx/PMS) process. Free radical quenching experiments and electron spin resonance (ESR) measurements demonstrated that both hydroxyl radical (HO?) and sulfate radical (SO4?-) contributed to the degradation of Cu-EDTA. Activation of PMS by Ti3C2Tx initiated Cu-EDTA decomplexation and released free Cu ions. Then, the formation of Ti-O-Cu bonds between Cu ions and Ti3C2Tx accelerated the electron transfer from Ti3C2Tx to Cu(Ⅱ) and triggered Cu(Ⅱ)/Cu(Ⅰ) cycle, which further enhanced PMS activation and led to the self-catalyzed decomplexation of Cu-EDTA. Simultaneous recovery of Cu was achieved due to the excellent absorption performance of negative charged Ti3C2Tx towards Cu ions. This study revealed the self-catalyzed decomplexation mechanism of Cu-EDTA in the Ti3C2Tx/PMS process and provided a feasible strategy for heavy metal complexes treatment.
查看更多>>摘要：? 2022 Elsevier B.V.In order to decrease the electricity consumption of water electrolysis, we investigated a novel hydrazine-assisted water electrolysis for electricity-independent hydrogen production, featuring with lower anodic hydrazine oxidation reaction (HzOR) than cathodic hydrogen evolution reaction (HER). The adsorption and semiconductor characteristics of hierarchical porous CoNS@CuPD, interlacing by Co(OH)2 nanosheets on the Cu dendrites surface, are selectively modified to optimize anodic HzOR and cathodic HER performance through doping B and P heteroatoms, respectively. The working potential of HzOR on B-doped CoNS@CuPD negatively shifts to ? 146 mV at 10 mA cm?2, while that of HER on P-doped CoNS@CuPD positively shifts to ? 70 mV. Consequently, the hydrazine electrolysis device using B-/P-doped catalysts output a small voltage of 60 mV at 10 mA cm?2, achieving co-generation of hydrogen and electricity for the first time. This work brings an intrinsic break in hydrogen-rich molecule-assisted water electrolysis for hydrogen production.
查看更多>>摘要：? 2022 Elsevier B.V.Feasibility of improving photocatalytic ozonation (PCO) activity of g-C3N4 (CN) by doping halogen (F, Cl, Br and I) was evaluated from the aspect of O3/O2 mass transfer and photogenerated electron (e-) and hole (h+) recombination. All halogen-CN had better activity (F-CN>I-CN>Cl-CN>Br-CN) for degrading ATZ than that of CN. Experimental and theoretical simulations results showed that doping halogen made the electron unevenly distributed and formed hydrophobic sites on CN, narrowed Eg of CN and enlarged e- migration space. The above properties were favorable for enhancing mass transfer of O3/O2 and suppressed e--h+ recombination. Besides, they either upshifted CB (C-I) or downshifted VB (C-F, C-Cl) to enhance the oxidation function of ?OH or h+. One-electron reduction (high e- utilization) of O3 was weakened and three-electron reduction (low e- utilization) of O2 was enhanced with decrease of halogen electronegativity. This work provided insights into catalyst design for PCO process.
查看更多>>摘要：? 2022 Elsevier B.V.Electrochemical CO2 conversion into valuable products provides a promising solution for achieving a carbon-neutral energy cycle. Herein, an active and stable Bi/Nafion interface is fabricated over Bi nanosheets with the modification of Nafion, which exhibits superior CO2 conversion with formate selectivity of above 95% in a wide potential range, partial current density of 72.12 mA cm?2 at ? 1.07 V vs. RHE in H-type cell. The extraordinary CO2 reduction performance could be ascribed to a high CO2 permeability and enhanced local proton activity at the Bi/Nafion interface, which leads to promoted CO2 adsorption and feasible proton-coupled electron transfer during the CO2 reduction process. Computational investigations reveal the modification of Nafion offers a comfortable platform to enable the key intermediate *OCHO to be stable. This work offers a valuable insight into interfacial manipulation of electrodes to convert CO2 to valuable products.
查看更多>>摘要：? 2022 Elsevier B.V.Tailoring the hydrodeoxygenation capacity via the regulation of the electronic structure of the active site is still a significant challenge for hydrogenation of oxygenated substrates. Herein, we report the highly efficient bimetallic CoNi/HAP catalysts to promote the catalytic transfer hydrodecarbonylation of methyl stearate to heptadecane. Multiple characterizations reveal that the CoNi alloy nanoparticles with fcc structure exhibit strong electron coupling effect and enhanced adsorption of methyl stearate, leading to the improvement of catalytic activity. Specifically, the introduction of Ni changes the reaction pathway from methyl stearate → octadecanol over the Co/HAP catalyst to methyl stearate → heptadecane over CoNi/HAP catalysts. In situ Fourier transform infrared spectra, reaction kinetics and density functional theory calculation show that the heptadecane is mainly generated through hydrodecarbonylation (-CO) rather than hydrodecarboxylation (-COO) because the C[sbnd]C bond cleavage of oxygenated intermediate (RCH2CO) is greatly facilitated over the Ni active site of electron reconstructed CoNi alloy nanoparticles. Finally, the Co5Ni5/HAP catalyst exhibits excellent conversion (99.4%), heptadecane selectivity (98.2%) and catalyst stability. These insights revealed here could pave the way for the rational development of catalyst with high catalytic performance in the catalytic transfer hydrogenation system of fatty acids/esters.
查看更多>>摘要：? 2022 Elsevier B.V.As green chemistry, aqueous-phase reactions play a vital role in modern fine chemical synthesis. Herein, an encapsulated nickel in a hollow carbon sphere (Ni@HCS) catalyst was constructed to effectively catalyze an aqueous-phase hydrogenation-rearrangement tandem (AP-HRT) reaction, in which water was employed as the solvent and reactant simultaneously. The activity is relevant to the HCS and Ni loading. The optimal Ni@HCS catalyst can release 100% furfural conversion and 99.1% cyclopentanone selectivity at 150 °C and can maintain its activity after 10 cycles of experiments. The superior catalytic performance comes from the fact that each independent Ni@HCS can be treated as an individual nanoreactor with a void-confinement effect, which not only reduces the side reactions due to the size-selective effect but also prevents active metal from leaching under harsh conditions. The reaction mechanism of FAL AP-HRT was further investigated via kinetic experiments combined with DFT calculations.
查看更多>>摘要：? 2022 Elsevier B.V.Defect structures of semiconductors intrinsically regulate the trap states, excitons and active charge carriers for artificial photosynthesis systems. A g-C3N4 system with abundant nitrogen defects was prepared through a thermal polycondensation strategy to reveal the role of trap states and exhibited a 20-fold enhanced H2 evolution efficiency relative to bulk g-C3N4 under visible light irradiation. Subsequent femtosecond transient absorption spectroscopy study found that the N-defect induced shallow trap states can capture photogenerated electrons to inhibit deep trapping and direct recombination of photogenerated charges. The active electrons in shallow trap states can enhance the photocatalytic H2 evolution when compared with the inactive electrons in deep trap states. Mid-infrared transient absorption spectroscopy also confirmed the increased quantity of shallow-trapped electrons without interference of other signals. This work provides new insights for steering depth of trap states and photocatalytic processes through N defects to achieve high photocatalytic performance using femtosecond transient absorption spectroscopy.
查看更多>>摘要：? 2022NiFe layered double hydroxide (NiFe-LDH), as a promising non-noble catalyst for oxygen evolution reaction (OER), suffers from the high OER barriers during NixFe1?x(OH)2/NixFe1?xOOH interconversion. To solve this problem, we highly dispersed the 2–3 nm CeO2?x particles on single-layered NiFe-LDH to form CeO2?x/NiFe-LDH heterostructure by a one-step co-precipitation method. CeO2?x, as an electron acceptor, can extract electrons from Ni sites of NiFe-LDH via Ni-O-Ce electron exchange effect, thus achieving direct Ni2+/Ni3+ electron transfer with no need of NixFe1?x(OH)2/NixFe1?xOOH phase transformation. As a result of efficient electron transfer by strong interface interactions between CeO2?x and NiFe-LDH, the CeO2?x/NiFe-LDH exhibits excellent OER performance with a low OER overpotential of 216 mV at 10 mA cm?2 and a Tafel slope of 74.1 mV dec?1. Our work provides a new strategy to improve the OER performances of NiFe-based materials.
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