Ni-Co-B nanoparticle decorated carbon felt by electroless plating as a bi-functional catalyst for urea electrolysis

Facilitated uranium and organic removal and electricity production via a zinc oxide/carbon felt cathode equipped hybrid tandem photocatalytic fuel cell

The combined pollution by uranium and organic matter has posed a serious challenge in the treatment of radioactive wastewater, while traditional treatment methods suffered from the problems of poor treatment efficiency and difficult recycling. Therefore, this study developed a novel hybrid tandem photocatalytic fuel cell (HTPFC) system which decorated with a ZnO modified carbon felt (ZnO/CF) cathode. This HTPFC not only efficiently removed UO22+ and organic matter while generating electricity, but can also be quickly disassembled and reassembled. The ZnO loading greatly improved the electrochemical properties of CF and introduced abundant active sites, making the constructed HTPFC exhibited excellent applicability, reusability and practical application prospects. When UO22+ coexisted with various organics, such as p-nitrophenol, ciprofloxacin, atrazine, ibuprofen, sulfamethoxazole, and tetracycline hydrochloride (TCH), the organic matter removal efficiencies were ≥94.36 %, and the UO22+ removal efficiencies were ≥94.56 %, accompanied with a maximum power output density of ≥1.31 mW·cm-2. After five cycles, the UO22+ and TCH removal efficiency still remained 92.34 % and 89.75 %, respectively. Notably, over 98.0 % of each of UO22+ and TCH can be removed under the actual sunlight illumination, indicating that the fabricated HTPFC had a great practical application potential. This study may present a new approach for disposing the complex wastewater containing heavy metals and organic compounds.

Development of a free-standing flexible electrode for efficient overall water-splitting performance via electroless deposition of iron-nickel-cobalt on polyacrylonitrile-based carbon cloth

Developing cost-effective and highly efficient electrodes for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is crucial, particularly for alkaline OER and HER. Herein, electroless plating of iron-nickel-cobalt (Fe-Ni-Co) electrocatalyst on a flexible polyacrylonitrile (PAN)-based carbon cloth (CC) was performed to synthesize a free-standing catalytic electrode for bifunctional electrocatalysts. The three-dimensional porous backbone of PAN-based CC and the synergistic effect between Fe-Ni-Co and corresponding hydroxides result in outstanding OER and HER activities, that is low overpotentials of 230 and 150 mV at 10 mA cm-2 and Tafel slopes of 63 and 57.1 mV dec-1, respectively. Additionally, a complete alkaline electrolyzer was constructed using Fe-Ni-Co plated PAN-based CC as both the cathode and anode. When operated at 10 mA cm-2, this setup enabled efficient water splitting at a low potential of 1.57 V. This study provides new opportunities for the development of advanced Fe-Ni-Co electrocatalyst with superior bifunctional OER and HER performance and cost-effectiveness that are suitable for integration into PAN-based CC via electroless plating.

Bifunctional Electrocatalysts for Overall and Hybrid Water Splitting

Electrocatalytic water splitting driven by renewable electricity has been recognized as a promising approach for green hydrogen production. Different from conventional strategies in developing electrocatalysts for the two half-reactions of water splitting (e.g., the hydrogen and oxygen evolution reactions, HER and OER) separately, there has been a growing interest in designing and developing bifunctional electrocatalysts, which are able to catalyze both the HER and OER. In addition, considering the high overpotentials required for OER while limited value of the produced oxygen, there is another rapidly growing interest in exploring alternative oxidation reactions to replace OER for hybrid water splitting toward energy-efficient hydrogen generation. This Review begins with an introduction on the fundamental aspects of water splitting, followed by a thorough discussion on various physicochemical characterization techniques that are frequently employed in probing the active sites, with an emphasis on the reconstruction of bifunctional electrocatalysts during redox electrolysis. The design, synthesis, and performance of diverse bifunctional electrocatalysts based on noble metals, nonprecious metals, and metal-free nanocarbons, for overall water splitting in acidic and alkaline electrolytes, are thoroughly summarized and compared. Next, their application toward hybrid water splitting is also presented, wherein the alternative anodic reactions include sacrificing agents oxidation, pollutants oxidative degradation, and organics oxidative upgrading. Finally, a concise statement on the current challenges and future opportunities of bifunctional electrocatalysts for both overall and hybrid water splitting is presented in the hope of guiding future endeavors in the quest for energy-efficient and sustainable green hydrogen production.