Roughened Zn‐Doped Ru–Ti Oxide Water Oxidation Electrocatalysts by Blending Active and Activated Passive Components

Abstract

An approach to decreasing the overpotential, increasing the stability, and optimizing the noble‐metal composition of electrocatalysts for the oxygen evolution reaction (OER) in acidic media is demonstrated. Essential components of this approach are: 1) combining an active (unstable Ru) component with a dopant (Zn)‐activated passive (stable Ti) element, 2) blending these elements by co‐electrodeposition in an acidic environment in which dissolution of the unstable component (excess Ru) promotes roughness, and 3) further increasing the roughness of the resultant electrode through chemical inhomogeneity by the incorporation of Ti and through structural inhomogeneity by incorporation of Zn in RuO2. The composition of the electrode with the maximal activity is Ru0.258Ti0.736Zn0.006Ox, and its activity is four times higher than that of RuO2. The electrochemical stability towards the OER follows the order RuTiZn>RuTi>RuZn>Ru. This design strategy provides a facile method to improve activity without compromising stability.

Enhanced Water Oxidation Activity of the Cobalt(II,III) Oxide Electrocatalyst on an Earth‐Abundant‐Metal‐Interlayered Hybrid Porous Carbon Support

“…The Ti interlayer in the Ti‐modified carbon support was found to undergo oxidation, as evidenced from its XPS spectra (Figure S13 b), in which the three peaks of Ti 2p are found at binding energies of 455, 459.2, and 462.2 eV. The first and last peaks are assigned to the Ti 2p 3/2 and Ti 2p 1/2 states of metallic Ti, whereas the peak at a binding energy of 459.2 eV is assigned to Ti IV 2p 3/2 . The formation of the metal oxide lowers the electronic conductivity of the support, which thereby defeats the purpose of the metal interlayer.…”

“…), which are generally more stable in alkaline media and unstable in acidic media . These earth‐abundant electrocatalysts show promising results, and their catalytic activity can be improved in the following ways: 1) by enhancing the surface roughness of the electrode, which can increase the number of electroactive sites with the formation of edges and steps and the exposure of high Miller‐indexed surfaces; 2) the use of highly porous three‐dimensional electro‐ des . Apart from this, the electrical conductivity and electronegativity of a support, on which the electrocatalyst is deposited, also play crucial roles in determining electrocatalytic activity.…”

Microwave‐Assisted Solvothermal One‐Pot Synthesis of RuO2 Nanoparticles: First Insights of Its Activity Towards Oxygen and Chlorine Evolution Reactions

“…In order to evaluate the electrochemical cycle‐life of the coatings prepared by MWAS, the current density associated with O 2 evolution was followed in a voltammetry experiment at 50 mV s −1 during 50 cycles (Figure ) in the range from OCP to 1.6 V versus Ag/AgCl in 1 mol L −1 H 2 SO 4 . In this test, the current was normalized with respect to the maximum current at a potential of 1.3 V. This procedure enabled to evaluate catalyst ageing during a long‐term test based on the decrease of the current density, which is proportional to the rate of loss of active sites due to dissolution with potential cycling . As observed in Figure , the stability of Ti/RuO 2 prepared by MWAS is compromised after 5 cycles since the normalized current significantly dropped by more than 50% from its original value.…”

Electrochemical Cycling‐Induced Amorphization of Cobalt(II,III) Oxide for Stable High Surface Area Oxygen Evolution Electrocatalysts

“…The excellent chemical and mechanical stability, tuneable porosity and surface chemistry, high specific surface area, and excellent diversity in structure makes these MOFs derived suitable for electrocatalysis . This demands further improvement of electrocatalytic properties which can be achieved in following ways: 1) enhancing surface roughness of electrode which can increase the number of electrocatalytically active sites with formation of edges, steps and exposure of high‐Miller indexed surfaces, 2) use of highly porous three dimensional electrode, however, during assembling the electrode into device, the imposed clamping pressure has to be optimized so that porosity of three dimensional (3D) electrocatalyst is not significantly decreased while increasing contact with the current collector, (3) enhancing the conductivity of either electrocatalyst or support thereby reducing overall charge transport through electrode, (4) enhancing surface electrocatalytic activity either through doping or (5) support‐electrocatalyst interaction, (6) the specific activity of OER can also be increased either by altering the crystal structure (through polymorphic engineering) or through microstructure modification by introducing crystal defects, dislocations and grain boundaries…”