Iron, Tungsten Dual-Doped Nickel Sulfide as Efficient Bifunctional Catalyst for Overall Water Splitting.

Developing low-cost and highly efficient bifunctional catalysts for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) is a challenging problem in electrochemical overall water splitting. Here, iron, tungsten dual-doped nickel sulfide catalyst (Fe/W-Ni3S2) is synthesized on the nickel foam, and it exhibits excellent OER and HER performance. As a result, the water electrolyze based on Fe/W-Ni3S2 bifunctional catalyst illustrates 10 mA cm-2 at 1.69 V (without iR-compensation) and highly durable overall water splitting over 100 h tested under 500 mA cm-2. Experimental results and DFT calculations indicate that the synergistic interaction between Fe doping and Ni vacancy induced by W leaching during the in situ oxidation process can maximize exposed OER active sites on the reconstructed NiOOH species for accelerating OER kinetics, while the Fe/W dual-doping optimizes the electronic structure of Fe/W-Ni3S2 and the binding strength of intermediates for boosting HER. This study unlocks the different promoting mechanisms of incorporating Fe and W for boosting the OER and HER activity of Ni3S2 for water splitting, which provides significant guidance for designing high-performance bifunctional catalysts for overall water splitting.

Dynamic Active Sites in Electrocatalysis.

In-depth understanding of the real-time behaviors of active sites during electrocatalysis is essential for the advancement of sustainable energy conversion. Recently, the concept of dynamic active sites has been recognized as a potent approach for creating self-adaptive electrocatalysts that can address a variety of electrocatalytic reactions, outperforming traditional electrocatalysts with static active sites. Nonetheless, the comprehension of the underlying principles that guide the engineering of dynamic active sites is presently insufficient. In this review, we systematically analyze the fundamentals of dynamic active sites for electrocatalysis and consider important future directions for this emerging field. We reveal that dynamic behaviors and reversibility are two crucial factors that influence electrocatalytic performance. By reviewing recent advances in dynamic active sites, we conclude that implementing dynamic electrocatalysis through variable reaction environments, correlating the model of dynamic evolution with catalytic properties, and developing localized and ultrafast in-situ/operando techniques are keys to designing high-performance dynamic electrocatalysts. This review paves the way to the development of the next-generation electrocatalyst and the universal theory for both dynamic and static active sites.