Realizing stable and efficient overall water splitting is highly desirable for sustainable and efficient hydrogen production yet challenging because of the rapid deactivation of electrocatalysts during the acidic oxygen evolution process. Here, we report that the single-site Pt-doped RuO 2 hollow nanospheres (SS Pt-RuO 2 HNSs) with interstitial C can serve as highly active and stable electrocatalysts for overall water splitting in 0.5 M H 2 SO 4 . The performance toward overall water splitting have surpassed most of the reported catalysts. Impressively, the SS Pt-RuO 2 HNSs exhibit promising stability in polymer electrolyte membrane electrolyzer at 100 mA cm −2 during continuous operation for 100 hours. Detailed experiments reveal that the interstitial C can elongate Ru-O and Pt-O bonds, and the presence of SS Pt can readily vary the electronic properties of RuO 2 and improve the OER activity by reducing the energy barriers and enhancing the dissociation energy of * O species.
Amorphous materials have attracted increasing attention in diverse fields due to their unique properties, yet their controllable fabrications still remain great challenges. Here, we demonstrate a top-down strategy for the fabrications of amorphous oxides through the amorphization of hydroxides. The versatility of this strategy has been validated by the amorphizations of unitary, binary and ternary hydroxides. Detailed characterizations indicate that the amorphization process is realized by the variation of coordination environment during thermal treatment, where the M–OH octahedral structure in hydroxides evolves to M–O tetrahedral structure in amorphous oxides with the disappearance of the M–M coordination. The optimal amorphous oxide (FeCoSn(OH)6-300) exhibits superior oxygen evolution reaction (OER) activity in alkaline media, where the turnover frequency (TOF) value is 39.4 times higher than that of FeCoSn(OH)6. Moreover, the enhanced OER performance and the amorphization process are investigated with density functional theory (DFT) and molecule dynamics (MD) simulations. The reported top-down fabrication strategy for fabricating amorphous oxides, may further promote fundamental research into and practical applications of amorphous materials for catalysis.
Developing a versatile electrocatalyst with remarkable performance viable for pH-universal overall water splitting is increasingly important for the industrial production of renewable energy conversion. Herein, our theoretical calculations predicate that...
The physicochemical properties and catalytic performance of transition metals are highly phase-dependent. Ru-based nanomaterials are superior catalysts toward hydrogen evolution reaction (HER) and hydrogen oxidation reaction (HOR), but studies are mostly limited to conventional hexagonal-close-packed (hcp) Ru, mainly arising from the difficulty in synthesizing Ru with pure face-centered-cubic (fcc) phase. Herein, we report a crystal-phase-dependent catalytic study of MoO x -modified Ru (MoO x -Ru fcc and MoO x -Ru hcp) for bifunctional HER and HOR. MoO x -Ru fcc is proven to outperform MoO x -Ru hcp in catalyzing both HER and HOR with much higher catalytic activity and more durable stability. The modification effect of MoO x gives rise to optimal adsorption of H and OH especially on fcc Ru, which thus has resulted in the superior catalytic performance. This work highlights the significance of phase engineering in constructing superior electrocatalysts and may stimulate more efforts on phase engineering of other metal-based materials for diversified applications.
Developing high-performance bifunctional electrocatalysts towards hydrogen evolution/oxidation reaction (HER/HOR) holds great significance for efficiently utilizing hydrogen energy. In this work, a unique class of Mo-modified Ru nanosheet assemblies (Mo-Ru NSAs)...
catalyst surface to form the final product, which seriously hinders the progress of the reaction. [3,4] Although researchers have made significant progress in the design of catalysts, a large cell voltage is still needed to drive this process. Therefore, it is still highly desirable to design high-efficiency water-splitting electrocatalysts. Recently, ruthenium (Ru) has attracted special attention for water-splitting catalysis since its inherently excellent activity and far lower price than platinum (Pt) and iridium (Ir). [5-9] To date, various strategies have been applied to enhance the activity of the Ru-based catalysts, including turning the crystal phase, doping electrocatalysts with hetero atoms, alloying Ru with the transition metals, and so on forth. [7,10,11] In principle, since the electrocatalysis is usually carried out on the surface of a catalyst, controlling the surface structure of the catalyst is a more straightforward way to improve the catalytic performance. The high-index crystal facets have more coordination unsaturated atoms and more active sites, which is believed to be more active. [12-14] Nevertheless, there were fewer reports on controlling the Ru-based catalysts with high-index facets. To this end, the fine control of Ru-based catalysts is of great significance in both practical application and fundamental research. Shape control has realized huge success for developing efficient Pd/Ptbased nanocatalysts, but the control of Ru-based nanocrystals remains a formidable challenge due to the inherent anisotropy in hexagonal closedpacked nanocrystals. Herein, a class of unique RuCo nanoscrews (NSs) for water electrosplitting is successfully synthesized with rough surfaces and the exposure of steps and edges. Those high-index faceted RuCo NSs show superior performance for overall water electrosplitting, where a low cell voltage of 1.524 V (@ 10 mA cm −2) and excellent stability for more than 20 h (@ 10 mA cm −2) for overall water electrosplitting in 1 m KOH is achieved. The enhanced performance of RuCo NSs is due to the optimization of the binding energy with the intermediate species and the reduced energy barrier of water dissociation. Density functional theory calculations reveal that the RuCo NS structure intrinsically endows various ridges and edges, which create low coordinated Ru-and Co-sites. These active Ru-and Co-sites present high efficiencies in electronic exchange and transfer between adsorbing O species and nearby lattice sites, guaranteeing the high H 2 Osplitting activities. This present work opens up a new strategy for creating high-performance electrocatalysts for water splitting.
Breaking the bottleneck of hydrogen oxidation/evolution reactions (HOR/HER) in alkaline media is of tremendous importance for the development of anion exchange membrane fuel cells/water electrolyzers. Atomically dispersed active sites are known to exhibit excellent activity and selectivity toward diverse catalytic reactions. Here, a class of unique Rh2Sb nanocrystals with multiple nanobranches (denoted as Rh2Sb NBs) and atomically dispersed Rh sites are reported as promising electrocatalysts for alkaline HOR/HER. Rh2Sb NBs/C exhibits superior HER performance with a low overpotential and a small Tafel slope, outperforming both Rh NBs/C and commercial Pt/C. Significantly, Rh2Sb NBs show outstanding HOR performance of which the HOR specific activity and mass activity are about 9.9 and 10.1 times to those of Rh NBs/C, and about 4.2 and 3.7 times to those of Pt/C, respectively. Strikingly, Rh2Sb NBs can also exhibit excellent CO tolerance during HOR, whose activity can be largely maintained even at 100 ppm CO impurity. Density functional theory calculations reveal that the unsaturated Rh sites on Rh2Sb NBs surface are crucial for the enhanced alkaline HER and HOR activities. This work provides a unique catalyst design for efficient hydrogen electrocatalysis, which is critical for the development of alkaline fuel cells and beyond.
Photocatalytic hydrogen production is a prospective technology to solve the energy crisis and environmental problems. However, it is still challenging to produce hydrogen from photocatalytic water splitting on a large scale without a sacrificial agent and cocatalyst. Here, it is demonstrated that the dual doping of Ru/In single atoms on TiO2 (Ru‐In SA/TiO2) can modulate the separation of photogenerated carriers during the photocatalytic splitting of pure water. Impressively, the H2 evolution rate of Ru‐In SA/TiO2 reaches 174.1 µmol h−1, which is 6, 18, and 53 times higher than those of the Ru single‐atom decorated TiO2, In single‐atom decorated TiO2, and pristine TiO2, respectively. More importantly, Ru‐In SA/TiO2 outperforms most of the reported photocatalysts for photocatalytic water splitting in the absence of a sacrificial agent. Detailed investigations reveal that the decoration of Ru/In dual‐single atoms leads to the remarkable increase of Ti3+ and enrichment of oxygen vacancies, which accelerate the charge separation. In particular, the femtosecond transient absorption spectroscopy suggests that the doping of Ru single atom promotes the transfer of photogenerated electrons from TiO2 into Ru, while the doping of In single atom enhances the transfer of photogenerated holes from the TiO2 valence band to In single atoms, as a result of an efficient electron‐hole separation. This work not only provides an efficient photocatalyst for H2 production through pure water splitting in the absence of a sacrificial agent, but also promotes fundamental research on catalyst design and modification.
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