Overpotential

About: Overpotential is a research topic. Over the lifetime, 16474 publications have been published within this topic receiving 616632 citations.

Porous Nickel-Iron Selenide Nanosheets as Highly Efficient Electrocatalysts for Oxygen Evolution Reaction.

Abstract: Exploring non-noble and high-efficiency electrocatalysts is critical to large-scale industrial applications of electrochemical water splitting. Currently, nickel-based selenide materials are promising candidates for oxygen evolution reaction due to their low cost and excellent performance. In this work, we report the porous nickel–iron bimetallic selenide nanosheets ((Ni0.75Fe0.25)Se2) on carbon fiber cloth (CFC) by selenization of the ultrathin NiFe-based nanosheet precursor. The as-prepared three-dimensional oxygen evolution electrode exhibits a small overpotential of 255 mV at 35 mA cm–2 and a low Tafel slope of 47.2 mV dec–1 and keeps high stability during a 28 h measurement in alkaline solution. The outstanding catalytic performance and strong durability, in comparison to the advanced non-noble metal catalysts, are derived from the porous nanostructure fabrication, Fe incorporation, and selenization, which result in fast charge transportation and large electrochemically active surface area and enhanc...

Ultrathin amorphous cobalt–vanadium hydr(oxy)oxide catalysts for the oxygen evolution reaction

Abstract: Cost efficient and long-term stable catalysts are in great demand for the oxygen evolution reaction (OER), a key process involved in water splitting cells and metal–air batteries. Here, we demonstrate that the ultrathin amorphous cobalt–vanadium hydr(oxy)oxide we synthesized is a highly promising electrocatalytic material for the OER with a low overpotential of 0.250 V (even lower down to 0.215 V when supported on Au foam) at 10 mA cm−2 and a long stable operation time (170 h) in alkaline media. In combination with in situ X-ray absorption spectral characterization and first-principles simulations, we reveal that the ultrathin, amorphous and alloyed structural characteristics have enabled its facile transformation to the desirable active phase, leading to a dramatically enhanced catalytic activity. Our finding highlights the remarkable advantages of the two-dimensional amorphous material and sheds new light on the design of high-performance electrocatalysts.

Ultrathin Porous NiFeV Ternary Layer Hydroxide Nanosheets as a Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting

Abstract: Herein, the hydrothermal synthesis of porous ultrathin ternary NiFeV layer double hydroxides (LDHs) nanosheets grown on Nickel foam (NF) substrate as a highly efficient electrode toward overall water splitting in alkaline media is reported. The lateral size of the nanosheets is about a few hundreds of nanometers with the thickness of ≈10 nm. Among all molar ratios investigated, the Ni0.75 Fe0.125 V0.125 -LDHs/NF electrode depicts the optimized performance. It displays an excellent catalytic activity with a modest overpotential of 231 mV for the oxygen evolution reaction (OER) and 125 mV for the hydrogen evolution reaction (HER) in 1.0 m KOH electrolyte. Its exceptional activity is further shown in its small Tafel slope of 39.4 and 62.0 mV dec-1 for OER and HER, respectively. More importantly, remarkable durability and stability are also observed. When used for overall water splitting, the Ni0.75 Fe0.125 V0.125 -LDHs/NF electrodes require a voltage of only 1.591 V to reach 10 mA cm-2 in alkaline solution. These outstanding performances are mainly attributed to the synergistic effect of the ternary metal system that boosts the intrinsic catalytic activity and active surface area. This work explores a promising way to achieve the optimal inexpensive Ni-based hydroxide electrocatalyst for overall water splitting.

Gold Nanoclusters Promote Electrocatalytic Water Oxidation at the Nanocluster/CoSe2 Interface

Abstract: Electrocatalytic water splitting to produce hydrogen comprises the hydrogen and oxygen evolution half reactions (HER and OER), with the latter as the bottleneck process. Thus, enhancing the OER performance and understanding the mechanism are critically important. Herein, we report a strategy for OER enhancement by utilizing gold nanoclusters to form cluster/CoSe2 composites; the latter exhibit largely enhanced OER activity in alkaline solutions. The Au25/CoSe2 composite affords a current density of 10 mA cm–2 at small overpotential of ∼0.43 V (cf. CoSe2: ∼0.52 V). The ligand and gold cluster size can also tune the catalytic performance of the composites. Based upon XPS analysis and DFT simulations, we attribute the activity enhancement to electronic interactions between nanocluster and CoSe2, which favors the formation of the important intermediate (OOH) as well as the desorption of oxygen molecules over Aun/CoSe2 composites in the process of water oxidation. Such an atomic level understanding may provide...