Graphene/MoS2/FeCoNi(OH)x and Graphene/MoS2/FeCoNiPx multilayer-stacked vertical nanosheets on carbon fibers for highly efficient overall water splitting

Abstract

Development of excellent and cheap electrocatalysts for water electrolysis is of great significance for application of hydrogen energy. Here, we show a highly efficient and stable oxygen evolution reaction (OER) catalyst with multilayer-stacked hybrid structure, in which vertical graphene nanosheets (VGSs), MoS2 nanosheets, and layered FeCoNi hydroxides (FeCoNi(OH)x) are successively grown on carbon fibers (CF/VGSs/MoS2/FeCoNi(OH)x). The catalyst exhibits excellent OER performance with a low overpotential of 225 and 241 mV to attain 500 and 1000 mA cm−2 and small Tafel slope of 29.2 mV dec−1. Theoretical calculation indicates that compositing of FeCoNi(OH)x with MoS2 could generate favorable electronic structure and decrease the OER overpotential, promoting the electrocatalytic activity. An alkaline water electrolyzer is established using CF/VGSs/MoS2/FeCoNi(OH)x anode for overall water splitting, which generates a current density of 100 mA cm−2 at 1.59 V with excellent stability over 100 h. Our highly efficient catalysts have great prospect for water electrolysis.

Interfacial Atom‐Substitution Engineered Transition‐Metal Hydroxide Nanofibers with High‐Valence Fe for Efficient Electrochemical Water Oxidation

“…Combining the above results, we can conclude that the interfacial atom‐substitution strategy achieves higher controllability on electronic structures of V‐doped NiFe electrocatalysts compared with the conventional one‐pot strategy. Although the OER active sites of NiFe catalysts are controversial, it is increasingly convinced that the high‐valence transition metals, especially Fe, can optimize the OER intermediates’ free energy, thus enhancing the catalytic activity and kinetics [10c, 13b, 14, 22a] . In our NiFeV nanofiber electrocatalyst, the abundant formed high‐valence Fe via a charge transfer from Fe to V played an important role in optimizing the OER performance, and the Fe−O−V−O−Ni bridge could be recognized as the active site [17a] …”

“…Moreover, electrochemical impedance spectroscopy (EIS) has been performed to examine the electron‐transfer kinetics during the electrocatalytic process (Figure 4e). The semicircles in the high‐frequency zone are related to charge‐transfer resistance within electrodes (R H ), while the lower frequency region semicircles are attributed to charge‐transfer resistances at the electrode‐electrolyte interface (R L ) [17a, 22a, 27] . Both semicircle diameters apparently decrease in the order of NiFe, NiFeV, and NiFeV nanofibers, indicating the NiFeV nanofiber has the fastest electron‐transfer during OER.…”

Enhanced electrocatalytic activity of FeNi alloy quantum dot-decorated cobalt carbonate hydroxide nanosword arrays for effective overall water splitting

“…Considering the carbon-neutral target proposal, it is highly desirable to explore green and clean energy resources. [1][2][3][4] Electrocatalytic overall water splitting is considered one of the most promising and sustainable hydrogen production strategies. 5,6 Although noble metal-based materials such as Pt/ C and RuO 2 /IrO 2 for the hydrogen evolution reaction (HER) and OER at cathodic and anodic electrodes, respectively, have been considered to be the most advanced electrocatalysts, the high cost and shortage of raw materials greatly impede their large-scale application.…”

Fe incorporation-induced electronic modification of Co-tannic acid complex nanoflowers for high-performance water oxidation

“…The ever-increasing energy dilemma and environmental issues caused by the excessive depletion of finite traditional fossil fuels have stimulated considerable interest to seek clean, high-efficiency and sustainable energy. 1–6 Hydrogen has been widely deemed as one of the most promising energy carriers to satisfy the rapid-growing energy demand due to its high energy density and cleanliness. 7–10 Currently, electrochemical water splitting represents a readily-implemented and eco-friendly strategy to generate high-purity hydrogen.…”