Coordination engineering of iridium nanocluster bifunctional electrocatalyst for highly efficient and pH-universal overall water splitting

Abstract

Water electrolysis offers a promising energy conversion and storage technology for mitigating the global energy and environmental crisis, but there still lack highly efficient and pHuniversal electrocatalysts to boost the sluggish kinetics for both cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER). Herein, we report uniformly dispersed iridium nanoclusters embedded on nitrogen and sulfur co-doped graphene as an efficient and robust electrocatalyst for both HER and OER at all pH conditions, reaching a current density of 10 mA cm −2 with only 300, 190 and 220 mV overpotential for overall water splitting in neutral, acidic and alkaline electrolyte, respectively. Based on probing experiments, operando X-ray absorption spectroscopy and theoretical calculations, we attribute the high catalytic activities to the optimum bindings to hydrogen (for HER) and oxygenated intermediate species (for OER) derived from the tunable and favorable electronic state of the iridium sites coordinated with both nitrogen and sulfur.

Interstitial boron-triggered electron-deficient Os aerogels for enhanced pH-universal hydrogen evolution

“…In addition, the in-depth exploration of the real catalytic process and the identification of active-site structure are rarely available due to the structural remodeling, elemental valence changes and transformation of exposed active sites of electrocatalysts under realistic reaction conditions, probably resulting from additional electric potential, reaction temperature, or corrosive electrolyte 36 , 37 . In situ/operando characterizations, using X-ray absorption spectroscopy (XAS), offer an appropriate way to overcome these limitations, which can probe the changes in the dynamic electronic structure of catalysts and adsorbed intermediates during an actual reaction 38 – 40 . Therefore, from the perspective of basic research, the development and utilization of Os and the understanding of its electrocatalytic reaction mechanism at the atomic level are critical but utmost challenging for the rational design of future electrocatalysts with high performance.…”

Strategies for Electrochemically Sustainable H2 Production in Acid

“…[ 129 ] However, the element would suffer from slight dissolution especially during OER test (see Figure 6c ). 2) Heteroatom‐doped graphitized carbons [ 37 , 140 ] and W‐based materials [ 141 ] can be used as substrates because they are highly stable and their geometric and electronic structures are tunable, thus enabling further tailoring and optimization of intermediate binding.…”

Ultradispersed IrxNi clusters as bifunctional electrocatalysts for high-efficiency water splitting in acid electrolytes

“…Hydrogen energy as a clean energy has become a research hotspot in recent years. Electrolytic water 1,2 and fuel cells 3,4 are important devices for hydrogen energy generation and conversion. 5,6 These new technologies have been deemed to be clean, environmentally friendly and renewable, and they play extremely important roles in hydrogen energy technology.…”