Confining Zero‐Valent Platinum Single Atoms in α‐MoC_1−x for pH‐Universal Hydrogen Evolution Reaction

Abstract

Single-atom electrocatalysts (SACs) toward hydrogen evolution reaction (HER) have been extensively studied owing to their high mass activity and atom utilization. Although platinum (Pt) based SACs have been reported frequently, optimizing the metal-support interaction to achieve low valence state Pt species is still a challenge. Here, the carbon supported α-MoC 1−x nanoparticles are used to anchor zero-valent Pt single atoms (Pt SA /α-MoC 1−x @C) as electrocatalyst for pH-universal HER. The Pt SA /α-MoC 1−x @C with optimized Pt loading of 0.75 wt% shows a low overpotential (21, 12, and 36 mV at 10 mA cm -2 ) and high turnover frequencies (27.00, 31.98, and 21.39 H 2 s -1 at 100 mV) for HER under alkaline, acidic, and neutral electrolyte conditions. Experimental evidence combing density functional theory calculations confirm that the charge polarization leads to a zero-valence state of Pt single atom and further optimized the adsorption/desorption energy of intermediates, further accelerating the reaction dynamics for HER.

Atomically dispersed platinum supported onto nanoneedle-shaped protonated polyaniline for efficient hydrogen production in acidic water electrolysis

“…To evaluate the intrinsic activities of the Pt 1 -NPCNF and Pt 1 -FPCNF catalysts, we further investigated their specific activities through normalizing the current densities by their electrochemically active surface areas (ECSAs). In accord with previous studies about single-atom Pt catalysts [18,19,48,49], the ECSAs of the Pt 1 -NPCNF and Pt 1 -FPCNF catalysts were calculated based on their electrical double layer capacitors, which were obtained from cyclic voltammetry plots in a narrow non-Faradaic potential window (Figs S10 and S11). As shown in Fig.…”

“…In this regard, great efforts have been devoted to developing single-atom Pt catalysts, which can not only maximize the metal utilization efficiencies but also potentially deliver high catalytic activities [17][18][19][20][21][22]. It is noted that HER in acidic media takes place with the initial adsorption of hydrogen ions (H + ) on the active sites, followed by the formation of H* intermediates and then the generation of H 2 [23][24][25][26].…”

Re‐Dispersion of Platinum From CNTs Substrate to α‐MoC1 ‐ x to Boost the Hydrogen Evolution Reaction

“…It is well known that Pt 0 could serve as the active center toward HER. [ 27,32,33 ] The white‐line intensities of Pt L‐edge XANES for Pt/CNTs‐N and Pt/CNTs‐N + α‐MoC 1 ‐ x were both quite close to that of Pt foil, suggesting that the Pt species was mainly in zero valence state. And XPS results further revealed that the proportion of 59% for Pt 0 /(Pt 0 + Pt 2+ ) species in Pt/CNTs‐N catalyst increased to 76% in Pt/CNTs‐N + α‐MoC 1 ‐ x catalyst.…”

“…[ 22 ] As to the distribution of Pt 0 and Pt 2+ , the highest ratio of Pt 0 /(Pt 0 + Pt 2+ ) (87.9%) was detected over the Pt/α‐MoC 1 ‐ x sample (Table S1, Supporting Information), which is consistent with the strong electrophilicity of α‐MoC substrate. [ 27 ] While the lowest Pt 0 /(Pt 0 + Pt 2+ ) ratio of 59.0% was shown over Pt/CNTs‐N sample. Upon mixing with α‐MoC 1 ‐ x , the ratio of Pt 0 /(Pt 0 +Pt 2+ ) in Pt/CNTs‐N + α‐MoC 1 ‐ x was increased to 76.0%, indicating that the low valence state of Pt has an important connection with α‐MoC 1 ‐ x .…”

Constructing Pt and Pt/MoC Co‐Anchored on Nitrogen‐Doped Carbon Toward Excellent Methanol‐Resilient Oxygen Reduction Performance for Zinc‐Air Batteries

“…Recently, atomically dispersed platinum catalysts have shown great fascination in various electrochemical reactions. [12][13][14][15][16] Unfortunately, isolated Pt single atoms exhibit inactivity in O 2 reduction to H 2 O, a fourelectron process affecting conversion efficiency of metal-air batteries, due to the unfavorable absorption of oxygen molecules. [17,18] Besides, the low density of active sites in most single-atom catalysts may not sustainably meet the requirement of high output power density.…”