Highly Dispersed Mo Sites on Pd Nanosheets Enable Selective Ethanol-to-Acetate Conversion

Facile electrolysis-solvothermal synthesis of NiOx/graphene for enhanced ethanol oxidation to acetate

In this work, low-crystalized and defective NiOx/graphene was synthesized by a facile electrolysis-solvothermal method. In the electrolytic process, Ni ions originate from the Ni anode, and graphene is produced from the graphite cathode. Then, Ni ions are reduced into oxides and deposited on graphene in the subsequent solvothermal process. The NiOx/graphene displays excellent electrocatalytic activity and selectivity for ethanol oxidation reaction to acetate. The peak current density was 296.5 mA cm-2 on a glassy carbon electrode. The FE of acetate was more than 93% at the potential range between 1.4 and 1.7 V. We propose that the mechanism is a cooperation between the chemical deprotonating process of ethanol by Ni3+ species and the electrochemical oxidation of the CH3CH2O* intermediate to acetate at the interface between NiOx and graphene.

Nanostructure engineering of Pt/Pd-based oxygen reduction reaction electrocatalysts

Increasing the atomic utilization of Pt and Pd elements is the key to the advancement and broad dissemination of fuel cells. Central to this task is the design and fabrication of highly active and stable Pt- or Pd-based electrocatalysts for the oxygen reduction reaction (ORR), which requires a comprehensive understanding of the ORR pathways and mechanism. Past endeavors have accumulated a wealth of knowledge about the Pt/Pd-based ORR electrocatalysts based on structure engineering, while a systematic review of the nanostructure engineering of Pt/Pd-based ORR electrocatalysts has been rarely reported. In this review, we provide a systematic discussion about the current status of Pt/Pd-based ORR electrocatalysts from the perspective of nanostructure engineering, and we highlight the ORR pathways, mechanisms and theories in order to understand the ORR in a more complex nanocatalyst. Particularly, the underlying structure-function relationship of Pt/Pd-based ORR electrocatalysts is specifically highlighted, which will guide the future synthesis of more efficient ORR electrocatalysts.

CoFe-Layered Double Hydroxide Coupled with Pd Particles for Electrocatalytic Ethanol Oxidation

Electrocatalytic efficiency and stability have emerged as critical issues in the ethanol oxidation reaction (EOR) of direct ethanol fuel cells. In this paper, Pd/Co₁Fe₃-LDH/NF as an electrocatalyst for EOR was prepared by a two-step synthetic strategy. Metal-oxygen bonds formed between Pd nanoparticles and Co₁Fe₃-LDH/NF guaranteed structural stability and adequate surface-active site exposure. More importantly, the charge transfer of the formed Pd-O-Co(Fe) bridge could effectively modulate the electrical structure of hybrids, improving the facilitated absorption of OH^- radicals and oxidation of CO_ads. Benefiting from the interfacial interaction, exposed active sites, and structural stability, the observed specific activity for Pd/Co₁Fe₃-LDH/NF (17.46 mA cm^-2) was 97 and 73 times higher than those of commercial Pd/C (20%) (0.18 mA cm^-2) and Pt/C (20%) (0.24 mA cm^-2), respectively. Besides, the j_f/j_r ratio representing the resistance to catalyst poisoning was 1.92 in the Pd/Co₁Fe₃-LDH/NF catalytic system. These results provide insights into optimizing the electronic interaction between metals and the support of electrocatalysts for EOR.

Inhibitor and Activator: Dual Role of Subsurface Sulfide Enables Selective and Efficient Electro-Oxidation of Methanol to Formate on CuS@CuO Core-Shell Nanosheet Arrays

Selective electro-oxidation of aliphatic alcohols into value-added carboxylates at lower potentials than that of the oxygen evolution reaction (OER) is an environmentally and economically desirable anode reaction for clean energy storage and conversion technologies. However, it is challenging to achieve both high selectivity and high activity of the catalysts for the electro-oxidation of alcohols, such as the methanol oxidation reaction (MOR). Herein, a monolithic CuS@CuO/copper-foam electrode for the MOR with superior catalytic activity and almost 100% selectivity for formate is reported. In the core-shell CuS@CuO nanosheet arrays, the surface CuO directly catalyzes MOR, while the subsurface sulfide not only serves as an inhibitor to attenuate the oxidative power of the surface CuO to achieve selective oxidation of methanol to formate and prevent over-oxidation of formate to CO₂ but also serves as an activator to form more surface O defects as active sites and enhances the methanol adsorption and charge transfer to achieve superior catalytic activity. CuS@CuO/copper-foam electrodes can be prepared on a large scale by electro-oxidation of copper-foam at ambient conditions and can be readily utilized in clean energy technologies.

Introducing Te for boosting electrocatalytic reactions

The deployment of robust catalysts for electrochemical reactions is a critical topic for energy conversion techniques. Te-based nanomaterials have attracted increasing attention for their application in electrochemical reactions due to their positive influence on the electrocatalytic performance induced by their distinctive electronic and physicochemical properties. Herein, we have summarized the recent progress on Te-based nanocatalysts for electrocatalytic reactions by primarily focusing on the positive influence of Te on electrocatalysts. Firstly, Te-based nanomaterials can serve as an ideal template for the construction of well-defined nanostructures. Secondly, Te doping can significantly modify the electronic structure of the host catalyst, thereby, leading to the optimization of binding strength with intermediates. Furthermore, the Te etching strategy can also create a high density of surface defects, thereby leading to substantial improvement in the electrocatalytic performance. Additionally, many representative Te-based nanocatalysts for electrocatalytic reactions are also summarized and systematically discussed. Finally, a conclusive and perspective discussion is also provided to provide guidance for the future development of more efficient electrocatalysts.