Fabricated a novel CNT catalyst with Ru,Ni nanoparticles encapsulated inside and CeO 2 /RuO 2 heterojunctions outside. • Achieved lower OER/HER overpotentials of 163.9/105.8 mV at 10 mA cm −2 in 0.5 M H 2 SO 4 electrolyte. • Interfacial electron transfer of CeO 2 /RuO 2 heterojunction effectively inhibits Ru overoxidation and dissolution. • Exhibits outstanding bifunctional electrocatalytic performance in both acidic and alkaline water splitting. Proton exchange membrane (PEM) water electrolysis links renewable energy surplus utilization to hydrogen storage—a critical connection enabled by its rapid adaptation to renewable power output swings. Nevertheless, developing bifunctional electrocatalysts incorporating high activity, economic feasibility, and long-term stability remains insufficient for fluctuation-adapted acidic electrolyzers. Herein, we designed and synthesized a bifunctional electrocatalyst (denoted as CeO 2 /RuO 2 /Ru,Ni@CNT), in which Ru and Ni nanoparticles are encapsulated within carbon nanotubes, while CeO 2 /RuO 2 heterojunctions are distributed on the exterior surface. The catalyst was prepared via a combination of calcination, hydrothermal, and annealing processes. Experimental results show the catalyst has excellent bifunctional activity for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in 0.5 M H 2 SO 4 , with overpotentials as low as 163.9 mV (OER) and 105 mV (HER) at 10 mA cm −2 and good stability. The superior performance stems from the synergistic interactions of multiple factors, including the high dispersion and electrical conductivity of carbon nanotubes, the electronic modulation imparted by internal Ru and Ni nanoparticles, and the interfacial electron transfer at the CeO 2 /RuO 2 heterojunctions. This study establishes a new design direction for high-performance bifunctional electrocatalysts, relying on encapsulation-heterojunction structures, for renewable-coupled acidic PEM electrolysis. Download: Download high-res image (693KB) Download: Download full-size image
Jie Ding,Yusheng Wu,Shuyu Jia,Yuying Feng,Ke Li,Min Fang,Jianchun Bao,Yong Wu
Three 3D, anionic Cd(II) porphyrinic metal-organic frameworks (PMOFs), 1(3.5:1)-2d-120 ([Cd 3·2 (H 2 TCPP) 2 ][(CH 3 ) 2 NH 2 ] 1.6 ), its Li + -exchanged product (e.g. Li + -1-120 , formula: [Cd 3·2 (H 2 TCPP) 2 ]Li 1.6 ) and 1(10:1)-4d-120 ([Cd 3·7 H 2 TCPP) 2 ][(CH 3 ) 2 NH 2 ] 0.6 ) were synthesized, all of which have the same PXRD pattern. Their VB and CB band-edge positions were determined in nonaqueous electrolyte as −0.59, 1.12; −0.60, 1.11; and −0.60, 1.16, respectively. Their light absorption properties in the range of 250–2500 nm were obtained by UV–Vis-IR reflectance spectroscopy. Transient photocurrent responses, electrochemical impedance spectra (EIS) and solid state photoluminescence (PL) spectra of the three PMOFs were obtained. When irradiated using light of 430 nm and −0.5-0.5 bias potentials (versus Ag/Ag + electrode in CH 3 CN), both positive and negative photocurrent were observed. Mott-Schottky plot measurements indicate that they are intrinsic semiconductors. Although these three PMOFs can photocatalytically reduce CO 2 to CO in the absence of Ru (bpy) 3 Cl 2 , their catalytic abilities are very weak. The roles of these PMOFs in CH 3 CN/trimethylamine (TEA) or triethanolamine (TEOA)/H 2 O (400 μL)/Ru (bpy) 3 Cl 2 . 6H 2 O was found to be mainly cocatalysts, and Ru (bpy) 3 Cl 2 was the actual photocatalyst in the presence of small amounts of water (0–400 μL). These PMOFs act as cocatalysts due to the increased reducing power upon light irradiation . Reducing the charge of the framework can reduce the efficiencies of the photocatalytic CO 2 reduction to CO. Li + -1-120 was found to be able to react with Ru (bpy) 3 Cl 2 when sufficient amounts of H 2 O are present in CH 3 CN and TEA system, preventing the photocatalytic property of Ru (bpy) 3 Cl 2 to be released. In addition, we found that TEOA is a worse reducing agent than TEA, leading to much lower photocatalytic efficiency of the system. Mechanisms were proposed for reactions occurred in CH 3 CN/TEA (or TEOA)/H 2 O (400 μL)/Ru (bpy) 3 Cl 2 . 6H 2 O/PMOF system, and strategies to improve the photocatalytic performance of CO 2 reduction to CO were proposed.
The development of solid-oxide cells requires fuel electrodes capable of promoting highly catalytic activities for CO 2 electrochemical reduction (CO 2 R). This study develops a fuel electrode material, Sr(Ti 0·3 Fe 0·63 Ru 0.07 ) O 3-δ (STFR) perovskite, enhance with in-situ exsolved Fe–Ru nanoparticles (STFR–FeRu), demonstrating excellent electrochemical catalytic activity for CO 2 R, considerable stability, and high selectivity for CO 2 electrolysis. Notably, the study discovered for the first time that STFR–FeRu exhibits significantly enhanced catalytic activity in a CO 2 -containing atmosphere compares to that in hydrogen-based fuels. At 800 °C and 1.3 V, La 0·8 Sr 0.2 Ga 0.8 Mg 0·2 O 3-δ electrolyte-supported cells with STFR–FeRu fuel electrode, for direct CO 2 electrolysis, realizes a current density of 1.77 A cm −2 . This current density is 50 % higher than that of H 2 O electrolysis under the same conditions. Additionally, the cell achieves a current density of 1.54 A cm −2 for CO 2 –H 2 O co-electrolysis, with a high CO 2 electrolysis selectivity (CO concentration exceeding 60 % in the electrolysis products).
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