Theoretical Revelation and Experimental Verification Synergistic Electronic Interaction of V-Doped RuNi as an Efficient Bifunctional Electrocatalyst for Overall Water Splitting

Abstract

As an advanced technology in the preparation of a sustainable and clean hydrogen energy source, electrolysis of water splitting has attracted more and more research attention. Water electrolysis is an important step toward hydrogen economy on account of the high efficiency and environmentally friendly. However, developing bifunctional electrocatalysts possessed with low cost, high activity, and everlasting durability to simultaneously promote bulk water cleavage is imminent. In this work, transition metal oxide (TMOs) H x V2O5 was anchored on the RuNi bimetallic catalyst by hydrothermal method to form a porous granular catalyst, which greatly improved the electron transfer ability. Due to the increased contact surface between RuVONi and electrolyte of this structural catalyst, the amounts of active sites are ferreted out. In-depth experimental results and DFT calculations show optimized molar ratio RuNiVO sample has superior electron transport ability compared with RuNiV, RuNiMoO, and RuNiMo, and exhibits significant electrocatalytic performance at 1.0 M KOH. Under the current density of 10 mA cm–2, RuNiVO electrocatalysts show OER and HER overpotentials of 224 and 136 mV and have superior durability. The density functional theory (DFT) results indicate that the insertion V metal oxide may optimize ΔG with higher charge density intensity, thereby improving its OER and HER activities.

Vanadium-Doped Bimetallic Nanoporous Metal–Organic Frameworks as Bifunctional Electrocatalysts for Urea-Assisted Hydrogen Production

“…In a word, the importance and effectiveness of introducing vanadium into target M 2 V-MOFs have been fully proven based on XPS, Tafel slopes, ESCA, and EIS data. For target M 2 V-MOFs after introducing vanadium, significantly lower Tafel values as shown in Figures , , , and and Table and , much larger C dl and ESCA results, as well as much smaller EIS data than corresponding M 3 -MOFs with single metal centers have fully demonstrated their more rapid electron transfer rate, superior electrocatalytic kinetics, increased active sites, and higher electrical conductivity during the OER, UOR, HER, and HER­(U), which can explain such enhancement of electrocatalytic activity and performance for M 2 V-MOFs from M 3 -MOFs. ,,, …”

“…Figure d displays the high-resolution Fe 2p spectra of the samples, where the two peaks at around 711.3 and 725.1 V should be assigned to Fe 2p 3/2 and Fe 2p 1/2 of Fe 2+ species, and the other two peaks at 713.1 and 727.8 eV can be ascribed to the Fe 2p 3/2 and Fe 2p 1/2 of Fe 3+ species, respectively. Besides, the peak at 717.0 eV should correspond to the satellite peaks. , Compared with initial Fe 3 -MOF, the binding energies of Fe 2p in Fe 2 V-MOF shift to a higher binding energy region by about 0.3 eV, revealing strong electron interactions between Fe and V. In other words, vanadium can effectively adjust the electronic structure and chemical environment in target Fe 2 V-MOF, which is beneficial to accelerate the electron transfer and improve the electrocatalytic activity and cleavage rate of water. ,, The high-resolution V 2p XPS profile is shown in Figure e, where two peaks at 516.3 and 523.2 eV correspond to V 2p 3/2 and V 2p 1/2 of V 3+ , two peaks at 517.3 and 523.2 eV can be assigned to V 2p 3/2 and V 2p 1/2 of V 4+ , and two pairs of pronounced peaks at 518.9 and 525.6 eV can be attributed to V 2p 3/2 and V 2p 1/2 of V 5+ , respectively. , Therefore, the result of XPS further confirms that M 3 -MOFs and M 2 V-MOFs have been successfully prepared and also provides a clear demonstration of the synergistic effect between the V center and the M metal center.…”

Intercalated PtCo Electrocatalyst of Vanadium Metal Oxide Increases Charge Density to Facilitate Hydrogen Evolution

“…Under ambient temperature conditions, vanadium powder was gradually oxidized by H 2 O 2 in the existence of ethanol. Through the carefully controlled, sluggish reaction rate facilitated by ethanol, the solution-processed hydrogen metal oxide bronze H x V 2 O 5 was successfully obtained [22]. The H x V 2 O 5 color changed from yellow to brown during the preparation process, as can be seen in Figure S1.…”