Pig Bone Derived Hierarchical Porous Carbon-Supported Platinum Nanoparticles with Superior Electrocatalytic Activity Towards Oxygen Reduction Reaction

Cooperation between holey N-doped carbon and Ni nanoparticles as an efficient electrocatalyst for the hydrogen evolution reaction

Exploring non-noble and high-performance metal catalysts to replace platinum-based catalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting significantly alleviates environmental pollution and the energy crisis. However, the synthetic approaches of such electrocatalysts are generally complex and challenging for large-scale production. Herein, a facile and green solid-state synthesis of Ni nanoparticles decorated with N-doped porous carbon is presented. These materials are derived from chitosan as carbon, nitrogen sources, and nickel acetate as a nickel source with NaCl as a template. The synthesis procedure is simple to scale up without an organic solvent. Benefiting from its porous structure, splendid conductivity, and the synergistic effect of Ni nanoparticles and holey N-doped carbon, the as-prepared Ni@CN exhibits superior HER performance in 1 M KOH with a low potential of 121 mV at 10 mA cm-2. These findings indicate that the convenient and environmentally friendly synthesis approach provides a novel method for large-scale synthesis of HER electrocatalysts for industrial electrolytic water splitting applications.

Bioinspired and Bioderived Aqueous Electrocatalysis

The development of efficient and sustainable electrochemical systems able to provide clean-energy fuels and chemicals is one of the main current challenges of materials science and engineering. Over the last decades, significant advances have been made in the development of robust electrocatalysts for different reactions, with fundamental insights from both computational and experimental work. Some of the most promising systems in the literature are based on expensive and scarce platinum-group metals; however, natural enzymes show the highest per-site catalytic activities, while their active sites are based exclusively on earth-abundant metals. Additionally, natural biomass provides a valuable feedstock for producing advanced carbonaceous materials with porous hierarchical structures. Utilizing resources and design inspiration from nature can help create more sustainable and cost-effective strategies for manufacturing cost-effective, sustainable, and robust electrochemical materials and devices. This review spans from materials to device engineering; we initially discuss the design of carbon-based materials with bioinspired features (such as enzyme active sites), the utilization of biomass resources to construct tailored carbon materials, and their activity in aqueous electrocatalysis for water splitting, oxygen reduction, and CO2 reduction. We then delve in the applicability of bioinspired features in electrochemical devices, such as the engineering of bioinspired mass transport and electrode interfaces. Finally, we address remaining challenges, such as the stability of bioinspired active sites or the activity of metal-free carbon materials, and discuss new potential research directions that can open the gates to the implementation of bioinspired sustainable materials in electrochemical devices.

Advanced Biomass-Derived Electrocatalysts for the Oxygen Reduction Reaction

Recent progress in advanced nanostructures synthesized from biomass resources for the oxygen reduction reaction (ORR) is reviewed. The ORR plays a significant role in the performance of numerous energy-conversion devices, including low-temperature hydrogen and alcohol fuel cells, microbial fuel cells, as well as metal-air batteries. The viability of such fuel cells is strongly related to the cost of the electrodes, especially the cathodic ORR electrocatalyst. Hence, inexpensive and abundant plant and animal biomass have become attractive options to obtain electrocatalysts upon conversion into active carbon. Bioresource selection and processing criteria are discussed in light of their influence on the physicochemical properties of the ORR nanostructures. The resulting electrocatalytic activity and durability are introduced and compared to those from conventional Pt/C-based electrocatalysts. These ORR catalysts are also active for oxygen or hydrogen evolution reactions.

Hydrothermal Synthesis of Highly Dispersed Co3O4 Nanoparticles on Biomass-Derived Nitrogen-Doped Hierarchically Porous Carbon Networks as an Efficient Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions

Developing high-performance bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of vital importance in energy storage and conversion systems. Herein, we demonstrate a facile hydrothermal synthesis of highly dispersed Co₃O₄ nanoparticles (NPs) anchored on cattle-bone-derived nitrogen-doped hierarchically porous carbon (NHPC) networks as an efficient ORR/OER bifunctional electrocatalyst. The as-prepared Co₃O₄/NHPC exhibits a remarkable catalytic activity toward both ORR (outperforming the commercial Pt/C) and OER (comparable with the commercial RuO₂ catalyst) in alkaline electrolyte. The superior bifunctional catalytic activity can be ascribed to the large specific surface area (1070 m² g^-1), the well-defined hierarchically porous structure, and the high content of nitrogen doping (4.93 wt %), which synergistically contribute to the homogeneous dispersion of Co₃O₄ NPs and the enhanced mass transport capability. Moreover, the primary Zn-air battery using the Co₃O₄/NHPC cathode demonstrates a superior performance with an open-circuit potential of 1.39 V, a specific capacity of 795 mA h g_Zn^-1 (at 2 mA cm^-2), and a peak power density of 80 mW cm^-2. This work delivers a new insight into the design and synthesis of high-performance bifunctional nonprecious metal electrocatalysts for Zn-air battery and other electrochemical devices.