Insight on Tafel slopes from a microkinetic analysis of aqueous electrocatalysis for energy conversion.
TLDR
Detailed kinetic analyses of aqueous electrochemistry involving gaseous H2 or O2 involving hydrogen evolution reaction, hydrogen oxidation reaction, oxygen reduction reaction, and oxygen evolution reaction are revisited and the limitation of Butler-Volmer expression in electrocatalysis is discussed.Abstract:
Microkinetic analyses of aqueous electrochemistry involving gaseous H2 or O2, i.e., hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are revisited. The Tafel slopes used to evaluate the rate determining steps generally assume extreme coverage of the adsorbed species (θ ≈ 0 or ≈1), although, in practice, the slopes are coverage-dependent. We conducted detailed kinetic analyses describing the coverage-dependent Tafel slopes for the aforementioned reactions. Our careful analyses provide a general benchmark for experimentally observed Tafel slopes that can be assigned to specific rate determining steps. The Tafel analysis is a powerful tool for discussing the rate determining steps involved in electrocatalysis, but our study also demonstrated that overly simplified assumptions led to an inaccurate description of the surface electrocatalysis. Additionally, in many studies, Tafel analyses have been performed in conjunction with the Butler-Volmer equation, where its applicability regarding only electron transfer kinetics is often overlooked. Based on the derived kinetic description of the HER/HOR as an example, the limitation of Butler-Volmer expression in electrocatalysis is also discussed in this report.read more
Citations
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TL;DR: The physicochemical characteristics of spinels such as their compositions, structures, morphologies, defects, and substrates have been rationally regulated through various approaches and can yield spinels with improved ORR/OER catalytic activities, which can further accelerate the speed, prolong the life, and narrow the polarization of fuel cells, metal-air batteries, and water splitting devices.
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Precision and correctness in the evaluation of electrocatalytic water splitting: revisiting activity parameters with a critical assessment
Sengeni Anantharaj,Sengeni Anantharaj,Sivasankara Rao Ede,Sivasankara Rao Ede,Kannimuthu Karthick,Kannimuthu Karthick,Selvasundarasekar Sam Sankar,Selvasundarasekar Sam Sankar,Kumaravel Sangeetha,Kumaravel Sangeetha,Pitchiah Esakki Karthik,Subrata Kundu,Subrata Kundu +12 more
TL;DR: In this paper, the authors have discussed the use and validity of ten important parameters, namely overpotential at a defined current density, iR-corrected over-potential, Tafel slope, exchange current density (j0), mass activity, specific activity, faradaic efficiency (FE), turnover frequency (TOF), electrochemically active surface area (ECSA), and measurement of double layer capacitance (Cdl) for different electrocatalytic materials that are frequently employed in both oxygen evolution reaction (OER) and HER.
Journal ArticleDOI
High Performance Bifunctional Porous Non-Noble Metal Phosphide Catalyst for Overall Water Splitting
Fang Yu,Fang Yu,Haiqing Zhou,Haiqing Zhou,Yufeng Huang,Jingying Sun,Fan Qin,Jiming Bao,William A. Goddard,Shuo Chen,Zhifeng Ren +10 more
TL;DR: A hybrid catalyst constructed by iron and dinickel phosphides on nickel foams that drives both the hydrogen and oxygen evolution reactions well in base, and thus substantially expedites overall water splitting is reported, which outperforms the integrated iridium (IV) oxide and platinum couple (1.57 V).
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