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1. Atomically Dispersed Single Ni Site Catalysts for Nitrogen Reduction toward Electrochemical Ammonia Synthesis Using N 2 and H 2 O

   https://doi.org/10.1002/smtd.201900821  

   Mukherjee, Shreya ; Yang, Xiaoxuan ; Shan, Weitao ; Samarakoon, Widitha ; Karakalos, Stavros ; Cullen, David A. ; More, Karren ; Wang, Maoyu ; Feng, Zhenxing ; Wang, Guofeng ; et al ( February 2020 , Small Methods)

   Ammonia (NH₃) electrosynthesis gains significant attention as NH₃is essentially important for fertilizer production and fuel utilization. However, electrochemical nitrogen reduction reaction (NRR) remains a great challenge because of low activity and poor selectivity. Herein, a new class of atomically dispersed Ni site electrocatalyst is reported, which exhibits the optimal NH₃yield of 115 µg cm⁻²h⁻¹at –0.8 V versus reversible hydrogen electrode (RHE) under neutral conditions. High faradic efficiency of 21 ± 1.9% is achieved at ‐0.2 V versus RHE under alkaline conditions, although the ammonia yield is lower. The Ni sites are stabilized with nitrogen, which is verified by advanced X‐ray absorption spectroscopy and electron microscopy. Density functional theory calculations provide insightful understanding on the possible structure of active sites, relevant reaction pathways, and confirm that the Ni‐N₃sites are responsible for the experimentally observed activity and selectivity. Extensive controls strongly suggest that the atomically dispersed NiN₃site‐rich catalyst provides more intrinsically active sites than those in N‐doped carbon, instead of possible environmental contamination. This work further indicates that single‐metal site catalysts with optimal nitrogen coordination is very promising for NRR and indeed improves the scaling relationship of transition metals.

    

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2. A non-enzymatic glucose sensor based on a CoNi 2 Se 4 /rGO nanocomposite with ultrahigh sensitivity at low working potential

   https://doi.org/10.1039/c9tb00104b  

   Amin, Bahareh Golrokh ; Masud, Jahangir ; Nath, Manashi ( April 2019 , Journal of Materials Chemistry B)

   Uniform and porous CoNi 2 Se 4 was successfully synthesized by electrodeposition onto a composite electrode comprising reduced graphene oxide (rGO) anchored on a Ni foam substrate (prepared hydrothermally). This CoNi 2 Se 4 –rGO@NF composite electrode has been employed as an electrocatalyst for the direct oxidation of glucose, thereby acting as a high-performance non-enzymatic glucose sensor. Direct electrochemical measurement with the as-prepared electrode in 0.1 M NaOH revealed that the CoNi 2 Se 4 –rGO nanocomposite has excellent electrocatalytic activity towards glucose oxidation in an alkaline medium with a sensitivity of 18.89 mA mM −1 cm −2 and a wide linear response from 1 μM to 4.0 mM at a low applied potential of +0.35 V vs. Ag|AgCl. This study also highlights the effect of decreasing the anion electronegativity on enhancing the electrocatalytic efficiency by lowering the potential needed for glucose oxidation. The catalyst composite also exhibits high selectivity towards glucose oxidation in the presence of several interferents normally found in physiological blood samples. A low glucose detection limit of 0.65 μM and long-term stability along with a short response time of approximately 4 seconds highlights the promising performance of the CoNi 2 Se 4 –rGO@NF electrode for non-enzymatic glucose sensing with high precision and reliability. 

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3. Hydrogenated TiO 2 Carbon Support for PtRu Anode Catalyst in High‐Performance Anion‐Exchange Membrane Fuel Cells

   https://doi.org/10.1002/smll.202307497  

   Douglin, John C. ; Sekar, Archana ; Singh, Ramesh K. ; Chen, Zihua ; Li, Jun ; Dekel, Dario R. ( December 2023 , Small)

   The availability of durable, high‐performance electrocatalysts for the hydrogen oxidation reaction (HOR) is currently a constraint for anion‐exchange membrane fuel cells (AEMFCs). Herein, a rapid microwave‐assisted synthesis method is used to develop a core–shell catalyst support based on a hydrogenated TiO₂/carbon for PtRu nanoparticles (NPs). The hydrogenated TiO₂provides a strong metal‐support interaction with the PtRu NPs, which improves the catalyst's oxophilicity and HOR activity compared to commercial PtRu/C and enables greater size control of the catalyst NPs. The as‐synthesized PtRu/TiO₂/C‐400 electrocatalyst exhibits respectable performance in an AEMFC operated at 80 °C, yielding the highest current density (up to 3× higher) within the catalytic region (compared at 0.80–0.90 V) and voltage efficiency (68%@ 0.5 A cm⁻²) values in the compared literature. In addition, the cell demonstrates promising short‐term voltage stability with a minor voltage decay of 1.5 mV h⁻¹. This “first‐of‐its‐kind in alkaline” work may open further research avenues to develop rapid synthesis methods to prepare advanced core–shell metal‐oxide/carbon supports for electrocatalysts for use in the next‐generation of AEMFCs with potential applicability to the broader electrochemical systems research community.

    

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4. Highly Selective Oxygen Reduction to Hydrogen Peroxide on a Carbon-Supported Single-Atom Pd Electrocatalyst

   https://doi.org/10.1021/acscatal.1c05633  

   Wang, Nan ; Zhao, Xunhua ; Zhang, Rui ; Yu, Saerom ; Levell, Zachary H. ; Wang, Chunyang ; Ma, Shaobo ; Zou, Peichao ; Han, Lili ; Qin, Jiayi ; et al ( March 2022 , ACS Catalysis)

   Selective electrochemical two-electron oxygen reduction is a promising route for renewable and on-site H2O2 generation as an alternative to the anthraquinone process. Herein, we report a high-performance nitrogen-coordinated single-atom Pd electrocatalyst, which is derived from Pd-doped zeolitic imidazolate frameworks (ZIFs) through one-step thermolysis. High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) combined with X-ray absorption spectroscopy verifies atomically dispersed Pd atoms on nitrogen-doped carbon (Pd-NC). The single-atom Pd-NC catalyst exhibits excellent electrocatalytic performance for two-electron oxygen reduction to H2O2, which shows ∼95% selectivity toward H2O2 and an unprecedented onset potential of ∼0.8 V versus revisable hydrogen electrode (RHE) in 0.1 M KOH. Density functional theory (DFT) calculations demonstrate that the Pd-N4 catalytic sites thermodynamically prefer *–O bond breaking to O–O bond breaking, corresponding to a high selectivity for H2O2 production. This work provides a deep insight into the understanding of the catalytic process and design of high-performance 2e– ORR catalysts. 

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5. Nanostructured Ternary Nickel‐Based Mixed Anionic (Telluro)‐Selenide as a Superior Catalyst for Oxygen Evolution Reaction

   https://doi.org/10.1002/ente.202300177  

   Abdullahi, Ibrahim Munkaila ; Thomas, Siby ; Gagliardi, Alessio ; Zaeem, Mohsen Asle ; Nath, Manashi ( April 2023 , Energy Technology)

   Developing protocols for designing high‐efficiency, durable, cost‐effective electrocatalysts for oxygen evolution reaction (OER) necessitates deeper understanding of structure–property correlation as a function of composition. Herein, it has been demonstrated that incorporating tellurium into binary nickel chalcogenide (NiSe) and creating a mixed anionic phase perturbs its electronic structure and significantly enhances the OER activity. A series of nanostructured nickel chalcogenides comprising a layer‐by‐layer morphology along with mixed anionic ternary phase are grown in situ on nickel foam with varying morphological textures using simple hydrothermal synthesis route. Comprehensive X‐ray diffraction, X‐ray photoelectron spectroscopy, and in situ Raman spectroscopy analysis confirms the formation of a trigonal single‐phase nanocrystalline nickel (telluro)‐selenide (NiSeTe) as a truly mixed anionic composition. The NiSeTe electrocatalyst exhibits excellent OER performance, with a low overpotential of 300 mV at 50 mA cm⁻²and a small Tafel slope of 98 mV dec⁻¹in 1 mKOH electrolyte. The turnover frequency and mass activity are 0.047 s⁻¹and 90.3 Ag⁻¹, respectively. Detailed electrochemical measurements also reveal enhanced charge transfer properties of the NiSeTe phase compared to the mixture of binaries. Density functional theory calculations reveal favorable OH adsorption energy in the mixed anionic phase compared to the binary chalcogenides confirming superior electrocatalytic property.

    

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