Electronic Structure Optimization of PdZn-Graphitic Carbon Nitride Nanocomposites as Electrocatalysts for Selective CO₂ to CO Conversion

Abstract

Herein, a novel PdZn/g-C 3 N 4 nanocomposite electrocatalyst, PdZnGCN, prepared from a facile hydrothermal reduction procedure for an efficient CO 2 to CO conversion has been examined. This composite catalyst reduces CO 2 at a thermodynamic overpotential of 0.79 V versus RHE with a 93.6% CO Faradaic efficiency and a CO partial current density of 4.4 mA cm –2 . Moreover, the turnover frequency for PdZnGCN reaches 20 974 h –1 with an average selectivity of 95.4% for CO after 1 h and an energy efficiency approaching 59%, which is superior to most reported noble metals and metal alloys as electrocatalysts. The enhanced catalytic activity of this nanocomposite is due to synergistic interactions between PdZn and g-C 3 N 4 as evidenced by optimum work function, zeta potential, CO desorption rate, and downshifted d-band center. Furthermore, suppressed grain growth during the formation of nanocomposites also results in faster reaction kinetics, as demonstrated by a lower Tafel slope (93.6 mV/dec) and a larger electrochemically active surface, consequently enhancing the overall performance.

Ternary CuZnPd Nanoalloys Achieving the Synergy of an Electronic Interaction and Bifunctional Catalysis for Efficient Ethanol Electrooxidation

“…As shown in Figure 3a−d,g,h, the Pd 3d peaks for the ternary CuZnPd-1, binary CuPd, and ZnPd alloy nanoparticles, as well as the commercial Pd/C catalyst, and the Cu 2p peaks of the ternary CuZnPd-1 and binary CuPd alloy nanoparticles could be deconvoluted into two pairs of doublets, in which the more intense doublet could be assigned to the metallic Pd and Cu, while the weaker doublet is attributed to the oxidized Pd and Cu. 24,27,28,31,46 For the Zn 2p peaks of the ternary CuZnPd-1 and binary ZnPd alloy nanoparticles (Figure 3e,f), only two peaks attributed to metallic Zn 2p 1/2 and Zn 2p 3/2 , respectively, could be identified. 46 Notably, the binding energies of the Pd 3d peak for CuPd nanoparticles display an evident positive shift relative to those of the Pd 3d peak for commercial Pd/C (Figure 3b,d), which might be ascribed to the compressive lattice strain of Pd by alloying with Cu, 24,27,29,31,33,34 and the electron flow from Pd to Cu, possibly owing to the half empty 4s band of Cu.…”

“…24,27,28,31,46 For the Zn 2p peaks of the ternary CuZnPd-1 and binary ZnPd alloy nanoparticles (Figure 3e,f), only two peaks attributed to metallic Zn 2p 1/2 and Zn 2p 3/2 , respectively, could be identified. 46 Notably, the binding energies of the Pd 3d peak for CuPd nanoparticles display an evident positive shift relative to those of the Pd 3d peak for commercial Pd/C (Figure 3b,d), which might be ascribed to the compressive lattice strain of Pd by alloying with Cu, 24,27,29,31,33,34 and the electron flow from Pd to Cu, possibly owing to the half empty 4s band of Cu. 22,32 However, the binding energies of the Pd 3d peak for the binary ZnPd alloy nanoparticles have an obvious negative shift relative to that for the commercial Pd/C catalyst (Figure 3c,d) owing to the electron flow from Zn to Pd due to the larger work function of Pd than that of Zn.…”

Nickel-nitrogen-carbon (Ni-N-C) electrocatalysts toward CO2 electroreduction: Advances, optimizations, challenges and prospects

“…Previous studies have demonstrated that rate-determining steps (RDS) may be (3) or (4), depending on the COOH* binding energy and the CO* desorption energy. [41,42] Therefore, the accurate regulation of the adsorption strength of key intermediates is fairly essential to exploit the reasonable electrocatalyst for reducing CO 2 to CO. [43,44] Notably, except the ECR process, hydrogen adsorption on the electrocatalyst surface needs to be considered, because that HER is the main competitor of ECR. Stronger H* binding ability is required to rise HER overpotential, which will help promote the occurrence of ECR.…”

Co-sensitization of Copper Indium Gallium Disulfide and Indium Sulfide on Zinc Oxide Nanostructures: Effect of Morphology in Electrochemical Carbon Dioxide Reduction

“…Converting carbon dioxide (CO 2 ) into valuable chemicals and fuels has made an impact on reducing our carbon footprint. − However, the high stability of CO 2 for conversion into different chemicals restricts the application. Therefore, the research community has focused on developing materials and systems for efficient CO 2 conversion by reducing the high activation energy of CO 2 . − It is possible to achieve CO 2 reduction via various routes, including photocatalytic and electrochemical conversion. − In this way, besides decreasing carbon emissions, value-added chemicals, such as methanol, hydrogen, formic acid, and syngas, can be produced. − Among these chemicals, formic acid stands out as an alternative to fossil fuels due to its advantages, such as being an energy-intensive material, having a high volumetric hydrogen density, and having enormous potential as an effective hydrogen storage vector . Typically, the most important factor in producing different types of chemicals, from formic acid to carbon monoxide and multicarbon hydrocarbons and oxygenates, is the selectivity of the used catalyst.…”