Bigger is Surprisingly Better: Agglomerates of Larger RuP Nanoparticles Outperform Benchmark Pt Nanocatalysts for the Hydrogen Evolution Reaction

Abstract

Although metallic ruthenium (Ru) is a potential electrocatalyst for the hydrogen evolution reaction (HER) to replace platinum (Pt) at a cost of only ≈4% of Pt, the persistent dissolution of Ru under operation conditions remains a challenge. Here, it is reported that agglomerates of large ruthenium phosphide (RuP) particles (L-RP, ≈32 nm) show outstanding HER performance in pH-universal electrolytes, which particularly demonstrates a surprisingly higher intrinsic activity and durability than small nanoparticles of RuP (S-RP, ≈3 nm) or metallic Ru on carbon supports. This is especially true in basic media, achieving electrocatalytic activity comparable to or even outperforming that of Pt/C, as reflected by lower overpotential at 10 mA cm , smaller Tafel slope, larger exchange current density, and higher turnover frequency while maintaining 200 h stable operation. Calculations suggest that ΔG of RuP is much closer to zero than that of metallic Ru, and phosphorous doping is proven to enhance the rate of proton transfer in HER, contributing in part to the improved activity of RuP. The better performance of L-RP than that of S-RP is ascribed largely to the stabilization of the P species due to the lowered surface energy of large particles. Furthermore, the relatively low-cost materials and facile synthesis make L-RP/C a highly attractive next-generation HER electrocatalyst.

Flexible Honeycombed Nanoporous/Glassy Hybrid for Efficient Electrocatalytic Hydrogen Generation

“…[8] Consequently, there is considerable interest in discovering cheaper HER catalysts with comparable performance to the commercially available Pt/C in alkaline media. [8] Consequently, there is considerable interest in discovering cheaper HER catalysts with comparable performance to the commercially available Pt/C in alkaline media.…”

Ruthenium Nanoparticles for Catalytic Water Splitting

“…Finally, although not a supported composite system, extremely active and stable (200 h at 10 mA cm −1 ) 32 nm RuP NP agglomerates on C (RuP/C, Table , entry 10; Table , entry 8) have been described at acidic and basic pH, with higher | j 0 | and TOF and lower η 10 and Tafel slopes than those of 20 % Pt/C at pH 14 and comparable values at pH 0. Curiously, the agglomerates show superior performance and stability to that of smaller sized NPs of 3 nm due to better stabilization of the P species for the former thanks to a lower surface energy of larger NPs …”

Downshifted d‐Band Center of Ru/MWCNTs by Turbostratic Carbon Nitride for Efficient and Robust Hydrogen Evolution in Alkali

“…[27,28] Furthermore, they also suffer from a serious metal bleaching in the electrolytes. [29] Recently, the consideration of Ru as a promising candidate or alternatives for HER has been realized through various strategies, [30][31][32][33][34][35][36][37][38][39][40] which can effectively improve their HER performance in both acidic and basic electrolytes. Anomalous Ru catalysts with new face-centered cubic (fcc) crystallographic structure deposited on g-C 3 N 4 /C exhibited 2.5 times higher turnover of frequency (TOF) than the 20 wt % Pt/C in alkaline solutions.…”