Pan Deng,Wang Yanan,Lin Liwei,Zhang Yuzhe,Zhou Man,Li Zhongyu,Xu Song
Photothermal catalytic CO 2 reduction can combine photocatalysis and thermal catalysis by using full-spectrum solar energy to convert CO 2 into high value-added chemicals. This can effectively alleviate the problems of excessive CO 2 emissions and thermal catalytic energy waste. In this paper, a novel catalyst was prepared using Ce-MOF as a precursor to generate Cu/Ni/CeO 2 for efficient reduction of CO 2 to CO by hydrogenation. Due to the rod-like structure of CeO 2 and the high dispersion of Cu and Ni nanoparticles, 10%Cu 5%Ni CeO 2 can achieve a catalytic activity of 54.21 mmol g −1 h −1 in the full solar spectrum. The supported Cu and Ni metals are the active sites for catalytic reduction. Meanwhile, Cu and Ni enhanced the light absorption ability of the catalyst and the surface temperature under illumination. This is due to the hot charge carriers generated by LSPR effect in Ni and Cu metal nanoparticles, which can dissipate energy through local heating, thus increasing the temperature of the catalyst under illumination. It can be found that the CO 2 reduction activity of photo-assisted thermocatalysis is higher than that of thermal catalysis under the same conditions. Therefore, the combined effect of the electrons generated by UV–Vis light and the heating effect of near-infrared light on catalyst could improve the catalytic activity. This work might provide a potential strategy for efficient photothermal reduction of CO 2 in the future.
Birnessite (δ-MnO 2 ), inspired by biological photosynthesis, holds promise as oxygen evolution reaction (OER) catalysts in water electrolysis for clean energy. Given that Mn 3+ serves as the active sites, various strategies have been employed to increase the Mn 3+ content to boost the OER activity. To surpass the limitations of the traditional adsorbate evolution mechanism (AEM), we have adopted an electrochemical reduction method to introduce metallic Ni and enrich oxygen vacancies onto δ-MnO 2 nanosheets. The resulting Ni/MnO 2 v /CC exhibits exceptional OER performance, with a reduction in overpotential by 190 mV (from 478 mV to 289 mV) at 10 mA cm −2 and a Tafel slope as low as 45 mV dec -1 , indicating accelerated catalytic activity. Experimental and theoretical analyses attribute this enhancement to a transition from the traditional AEM to lattice oxygen mechanism (LOM) mechanism. Moreover, the dual modification also enhances electronic conductivity, electrochemical surface area, and charge transfer ability of δ-MnO 2 . Our work offers a pathway to overcome conventional limitations in OER electrocatalysts, applicable not only to Mn-based catalysts but also to a range of other transition metal oxides.
Chenyu Yang,Xinru Ma,Yaohui Fan,Feiyu Zou,Wenjuan Bai,Dianming Chu,Haoxi Ben,Zhaoying Li,Yan He
The urgent need to address global energy shortages and environmental pollution has accelerated the development of renewable algal bio-oils. Spirulina stands out as an ideal feedstock for hydrothermal liquefaction (HTL) owing to its high carbon sequestration rate, non-competition with arable land, and rich protein-lipid content. However, Spirulina-derived bio-oil typically suffers from high oxygen content and low heating value. To overcome these limitations, this study developed a microwave-assisted two-stage HTL process integrated with a Ni-loaded, alkali-modified HZSM-5 catalyst. Unlike conventional catalysts that often rely on costly noble metals or suffer from diffusion limitations in microporous structures, this system employs earth-abundant nickel on a hierarchically structured zeolite to enhance both cost-effectiveness and catalytic efficiency. HZSM-5 was treated with NaOH to create mesoporosity, followed by Ni impregnation to introduce hydrogenation functionality. The effects of NaOH concentration and Ni loading on catalyst properties were systematically investigated. Process optimization was performed via response surface methodology using a 3 % sulfuric acid medium, and bio-oil composition was analyzed by GC/MS. Modification with 1 mol/L NaOH increased hydrocarbon content to 32.9 %, while subsequent loading with 5 wt% Ni synergistically boosted the yield to 48.1 %. Molecular dynamics simulations provided mechanistic insights into bond cleavage and conversion pathways of Spirulina-derived model compounds in subcritical water. Compared with existing catalytic systems, this study significantly improves the quality of biofuels, providing an efficient catalytic strategy and fundamental insights for the production of high-quality bio-oil from spirulina.
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