One-Pot Synthesis of Alloy Ir–Cu Microspheres with Excellent Electro-Catalytic Activity Toward Oxygen Evolution Reaction under Acidic Conditions

Abstract

The development of catalysts with high efficiency and stability in acidic electrolytes for oxygen evolution reaction (OER) is critical to water electrolyzers and renewable energy conversion and has been eagerly explored in the shape-controlled synthesis of noble metals such as Ir and Ru. However, the expensive prices of Ir and Ru severely hamper their wide use in OER. In this work, we show an efficient method for the one-pot synthesis of Ir0.4Cu0.6 microspheres. Electrochemical tests showed that the Ir–Cu microspheres as-synthesized delivered a prominent electrocatalytic activity toward OER in an acidic electrolyte with low overpotential (255 mV at 10 mA cm–2) and a small Tafel slope of 53.3 mV decade–1. They were much better than those of commercial Ir/C (331 mV at 10 mA cm–2 and Tafel slope of 100 mV decade–1). Moreover, the Ir0.4Cu0.6 as-synthesized also exhibited good stability for OER under acidic conditions, that is, after 30,000 s, the change of its potential was quite small in the chronopotentiometry test. The high catalytic performance could originate from the synergistic electronic interaction between iridium and copper atoms, which could modify the d-band center of iridium.

Regulating the Spin State of FeIII Enhances the Magnetic Effect of the Molecular Catalysis Mechanism

“…To further evaluate the electrocatalytic activity of catalysts, the electrochemically active surface area (ECSA) was measured, as depicted in Figure S9, showing that Cu 1 –Ni 6 Fe 2 –LDHs (87.6 μF cm –2 ) have more effective active sites compared with Cu 0 –Ni 6 Fe 2 –LDHs (39.0 μF cm –2 ); thus the Cu 2+ can effectively enhance site activity. With the increase of Cu 2+ content, the ECSA is decreased and the performance of OER is reduced, which is consistent with the results of Cu element doping catalysts in the literature. − The Tafel slopes were calculated to evaluate the OER kinetics, as shown in Figure c. The Tafel plots were derived from the polarization curves via the Tafel equation (η = b × log j + a , where η presented the overpotential, j the current density, and b the Tafel slope). − Compared with Cu 0 –Ni 6 Fe 2 –LDHs (101.6 mV dec –1 ), the Cu x –Ni 6 Fe 2 –LDHs ( x = 0.25, 0.5, 1, 2, 3) own lower Tafel slopes, indicating that the reaction kinetics can be enhanced by Cu 2+ doping.…”

Recent Progress in Transition-Metal Sulfide Catalyst Regulation for Improved Oxygen Evolution Reaction

“…The continuing consummation of traditional fossil energy has caused serious problems to the sustainable development of human society; − although an agreement has been made on the development of renewable energy technology, the large-scale applicant is still restricted by the intermittence character of this type of energy. − The water-splitting technique can solve this problem by transferring these renewable energies to the chemical energy of hydrogen for storage; thus, it has received increased attention recently. , Two half-reactions of oxygen evolution (OER, represented by the reaction H 2 O → O 2 + 4H + + 4e – ) and hydrogen evolution (HER, represented by the reaction 2H + + 2e – → H 2 ) are involved in this technique. Compared to the HER, OER is a more complex process that requires the transfer of four electrons; thus, the sluggish catalytic kinetics determines the entire efficiency of the water-splitting reaction. − To efficiently drive the electrolysis, active and robust electrocatalysts are required to catalyze both reactions to reduce the electrolysis overpotentials. − The precious metals and their oxides are excluded from large-scale application, because of the low reserve and high cost. , The alkaline water electrolysis technique that can employ a non-noble metal catalyst is one of the most promising methods for hydrogen production and becomes the current standard for industrial large-scale water electrolysis systems . Accordingly, much effort has been devoted to developing inexpensive and Earth-abundant catalysts that are based on transition metals (Fe, Co, Ni, etc.)…”

“…12−14 The precious metals and their oxides are excluded from large-scale application, because of the low reserve and high cost. 15,16 The alkaline water electrolysis technique that can employ a non-noble metal catalyst is one of the most promising methods for hydrogen production and becomes the current standard for industrial large-scale water electrolysis systems. 17 Accordingly, much effort has been devoted to developing inexpensive and Earth-abundant catalysts that are based on transition metals (Fe, Co, Ni, etc.)…”

Electrodeposition of a Three-Dimensional Nanostructure Composed of 2D Maple Leaf-like Rh Nanosheets for Formic Acid Oxidation

“…In recent years, due to the depletion of mineral resources and the deterioration of the environment, there is an urgent need to develop new energy conversion technologies. − Platinum group metals play an important role in this field because of their abundant surface-active sites and special active crystal faces. − Therefore, rational design and control of the shape (and surface structure) of precious metal nanocrystals (NCs) has become a powerful and versatile way to optimize the catalytic performances. − Among them, Rh has unique physical/chemical properties and excellent electrical properties, , chemical inertness, , mechanical strength, , and thermal stability. , Based on these advantages, Rh was widely used in various fields. For example, in the field of electrocatalysis, Rh was often used in the oxidation reaction of small molecules such as alcohols and formic acid. − …”