Transition‐Metal‐Doped RuIr Bifunctional Nanocrystals for Overall Water Splitting in Acidic Environments

• Published in: Advanced materials (Weinheim) Vol. 31; no. 17; pp. e1900510 - n/a
• Main Authors: Shan, Jieqiong, Ling, Tao, Davey, Kenneth, Zheng, Yao, Qiao, Shi‐Zhang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 25-04-2019
• Subjects: acidic environment; bifunctional electrocatalysis; Catalysis; Catalytic activity; composition‐activity relationship; Dependence; Electrocatalysts; Electronic structure; Hydrogen evolution reactions; Hydrogen fuels; Materials science; Nanocrystals; Nickel; Organic chemistry; overall water splitting; Oxygen evolution reactions; Transition metal alloys; transition metal doping; Transition metals; Water splitting; acidic environment; transition metal doping; composition-activity relationship; bifunctional electrocatalysis; overall water splitting
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201900510

The establishment of electrocatalysts with bifunctionality for efficient oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in acidic environments is necessary for the development of proton exchange membrane (PEM) water electrolyzers for the production of clean hydrogen fuel. RuIr alloy is considered to be a promising electrocatalyst because of its favorable OER performance and potential for HER. Here, the design of a bifunctional electrocatalyst with greatly boosted water‐splitting performance from doping RuIr alloy nanocrystals with transition metals that modify electronic structure and binding strength of reaction intermediates is reported. Significantly, Co‐RuIr results in small overpotentials of 235 mV for OER and 14 mV for HER (@ 10 mA cm−2 current density) in 0.1 m HClO4 media. Therefore a cell voltage of just 1.52 V is needed for overall water splitting to produce hydrogen and oxygen. More importantly, for a series of M‐RuIr (M = Co, Ni, Fe), the catalytic activity dependence at fundamental level on the chemical/valence states is used to establish a novel composition‐activity relationship. This permits new design principles for bifunctional electrocatalysts.
Transition‐metal‐doped RuIr alloy nanocrystals are synthesized as bifunctional overall water splitting electrocatalysts for acidic environments. Due to both increased active oxygen species concentration and modified surface site valence states, the dopants result in significantly high electrocatalytic performance. A novel composition–activity relationship is established. This can be applied to the rational design of bifunctional electrocatalysts.