Industrial nitrous oxide (N2O) emissions with high concentrations pose a significant challenge to climate change, while the oxidative dehydrogenation of propane (ODHP) with N2O presents a promising strategy for N2O valorization. However, the activity-selectivity trade-off and rapid deactivation by coke deposition remain challenges for future applications. Here, we select Pd/TiO2 as model catalysts and design spatially separated redox centers on the rutile phase catalyst (Pd/R-TiO2), which enable parallel adsorption and independent activation of C3H8 on metallic Pd sites and N2O on oxygen vacancies. Besides, it suppresses product overoxidation by reducing reactive oxygen species concentration near C3 intermediates, enhancing C3H6 selectivity while inhibiting enolic intermediate and coke formation to ensure catalyst stability. Hydrogen spillover from Pd sites to TiO2 surface connects the separated redox reactions, completing the catalytic cycle. This work presents a rational strategy for catalyst design in N2O-ODHP, contributing to the sustainable mitigation of non-CO2 greenhouse gases.
The electrocatalytic valorization of polyethylene terephthalate-derived ethylene glycol to valuable glycolic acid offers considerable economic and environmental benefits. However, conventional methods face scalability issues due to rapid activity decay of noble metal electrocatalysts. We demonstrate that a dynamic potential cycling approach, which alternates the electrode potential between oxidizing and reducing values, significantly mitigates surface deactivation of noble metals during electrochemical oxidation of ethylene glycol. This method enhances catalyst activity by 20 times compared to a constant-potential approach, maintaining this performance for up to 60 h with minimal deactivation. In situ Raman and X-ray absorption spectroscopy show that this effectiveness results from efficient removal of surface oxide during the reaction. The strategy is applicable to polyethylene terephthalate hydrolysates and various noble metals, such as palladium, gold, and platinum, with palladium showing a high conversion rate in recent studies. Our approach offers an efficient and durable method for electrochemical upcycling of biomass-derived compounds.
Zhiliang Feng,Zekun Geng,Shuzhen Pan,Yaru Yin,Xinzhi Sun,Xiaojuan Liu,Lei Ge,Feng Li
The electrocatalytic valorization of glycerol is an emerging upcycling process for the biomass utilization. In this work, nickel/sulfur-codoped laser-induced graphene (LINiSG) on flexible polyimide film was fabricated and demonstrated as a self-supported and binder-free monolithic electrode for electrocatalytic glycerol oxidation reaction (EGOR) towards the selective generation of value-added three-carbon (C3) chemicals. The laser-induced in-situ and synchronous carbonization of polysulfone and Ni precursor was demonstrated to remarkably promote both the electrochemical surface area and Ni loading of LINiSG electrode. These synergistic merits are considered as the main origin for its enhanced EGOR activity and stability, showing much smaller Tafel slope and 2-fold enhanced current density, as compared to LINiG electrode without the co-carbonization of polysulfone. The influence of experimental parameters has been systematically investigated by the product analysis, achieving an average 94.7 % C3 selectivity and 76.1 % C3 Faradaic efficiency with a high selectivity of dihydroxyacetone (ca. 67.7 %) in near-neutral conditions, which is better than most of the reported EGOR electrodes operated in near-neutral conditions. This work demonstrated the viability of using flexible self-supported and binder-free LIG electrode with rational design and preparation approach for electrocatalytic valorization of biomass.
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