Reported herein is elucidation of a novel Co-based oxygen evolution catalyst generated in situ from cobalt phosphide (CoP) nanoparticles. The present CoP nanoparticles, efficient alkaline hydrogen-evolving materials at the cathode, are revealed to experience unique metamorphosis upon anodic potential cycling in an alkaline electrolyte, engendering efficient and robust catalytic environments toward the oxygen evolution reaction (OER). Our extensive ex situ characterization shows that the transformed catalyst bears porous and nanoweb-like dispersed morphologies along with unique microscopic environments mainly consisting of discrete cobalt-oxo/hydroxo molecular units within a phosphate-enriched amorphous network. Outstanding OER efficiency is achievable with the activated catalyst, which is favorably comparable to even a precious iridium catalyst. A more remarkable feature is its outstanding long-term stability, superior to iridium and conventional cobalt oxide-based materials. Twelve-hour bulk electrolysis continuously operating at high current density is completely tolerable with the present catalyst.

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Single-atom catalysts (SACs) have attracted growing attention because they maximizet he number of active sites, with unpredictable catalytic activity.Despite numerous studies on SACs,t here is little researcho nt he support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SACb yc omparing with single-atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO 3Àx (Pt NP/WO 3Àx ). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO 3Àx (Pt SA/WO 3Àx ). The Pt SA/WO 3Àx exhibited ahigher degree of hydrogen spillover from Pt atoms to WO 3Àx at the interface, compared with Pt NP/WO 3Àx ,w hichd rastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides an ew framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs.Hydrogen is being pursued as af uture alternative to fossil fuels and an ideal energy carrier for renewable energy, because it has the highest energy density per mass without any pollutants.Currently,hydrogen production is primarily based on the steam reforming of fossil fuels,w hich is accompanied by environmental issues,s uch as as ubstantial increase in atmospheric CO 2 .Accordingly,itisnecessary to find sustainable and clean alternatives. [1] Electrochemical water splitting is considered ap otentially cost-effective and promising approach for clean hydrogen production. [2] Fort he cathodic hydrogen evolution reaction (HER), platinum (Pt)-based materials are known to the most active electrocatalysts,b ut the high cost and scarcity of Pt are key obstacles to commercial applications of water electrolyzers. [3] Hitherto,n umerous design strategies have been developed for nanostructured electrocatalysts to obtain outstanding electrochemical performance. [4] These strategies are shown to improve the utilization of Pt, and thereby to reduce the use of Pt. Fore xamples,c ore-shell [5] and hollow structures [6] can significantly improve Pt utilization by diminishing the buried non-active Pt atoms inside the particles. From this point of view,single-atom catalysts (SACs), where all metal species are individually dispersed on ad esired support, could be the best candidates to meet this goal, because they offer the maximum number of surface exposed Pt atoms.S everal studies have also demonstrated that Pt SACs show greatly boosted Pt mass activity compared to commercial Pt/C.However,research that considers the effect of the support on SACs performance for the HER is rarely found. [3,7] Thec hoice of support material is one of the most promising strategies for improving (electro)catalysis because interactions between the metal and support can drastically tune the electronic structure of the supported metal, and enhance performance. [8] Furthermore,i th as been recently reported that HER performance can be improved by not only changing the electronic structure of the supported m...

The electrochemical synthesis of NH 3 by the nitrogen reduction reaction (NRR) at low temperature (<65 °C) and atmospheric pressure using nanosized γ-Fe 2 O 3 electrocatalysts were demonstrated. The activity and selectivity of the catalyst was investigated both in a 0.1 M KOH electrolyte and when incorporated into an anion-exchange membrane electrode assembly (MEA). In a half-reaction experiment conducted in a KOH electrolyte, the γ-Fe 2 O 3 electrode presented a faradaic efficiency of 1.9% and a weight-normalized activity of 12.5 nmol h −1 mg −1 at 0.0 V RHE . However, the selectivity toward N 2 reduction decreased at more negative potentials owing to the competing proton reduction reaction. When the γ-Fe 2 O 3 nanoparticles were coated onto porous carbon paper to form an electrode for a MEA, their weight-normalized activity for N 2 reduction was found to increase dramatically to 55.9 nmol h −1 mg −1 . However, the weight-and area-normalized N 2 reduction activities of γ-Fe 2 O 3 decreased progressively from 35.9 to 14.8 nmol h −1 mg −1 and from 0.105 to 0.043 nmol h −1 cm −2 act , respectively, during a 25 h MEA durability test. In summary, a study of the fundamental behavior and catalytic activity of γ-Fe 2 O 3 nanoparticles in the electrochemical synthesis of NH 3 under low temperature and pressure is presented.

We have investigated the release of active sites blocked by bubbles attached on the surface of catalysts during the oxygen evolution reaction (OER) in alkaline water electrolysis, via the modulation of the wetting properties of the four different morphologies of a nickel catalyst.