Surface Reconstruction of Water Splitting Electrocatalysts

Abstract

Gibbs free energy (ΔG) of water splitting reaction is 237.2 kJ mol −1 , corresponding to a theoretical voltage of 1.23 V. [3] However, the existence of electrochemical/concentration polarization and solution resistance can increase the actual voltage of water electrolysis to much beyond 1.23 V. Particularly, the OER involves a complicated four-electron transfer process, which results in a sluggish kinetics thus has long been the bottleneck. [4] Therefore, it is necessary to explore efficient and robust electrocatalysts to reduce the overpotential of water electrolysis and the extra electric energy consumption. Although noble electrocatalysts, such as Pt, RuO 2 and IrO 2 , are recognized as the most efficient electrocatalysts for water electrolysis, their high scarcity and instability severely impede large-scale applications. [5] Recently, considerable effort has been focused on nonnoble transition-metal materials as viable alternatives for water splitting. Understanding the intrinsic catalytic mechanism and real active sites of these catalysts will benefit the rational design and application of high-efficiency catalysts.With the development of in situ characterization technologies, more reports have revealed that the original electrocatalyst (so-called "pre-catalyst") surface sites would undergo dynamic reconstruction and transform into real reactive species. [6] This in situ reconstruction process could tune the electrocatalytic behaviors such as adsorption, activation, and desorption, thus improving the catalytic performance. [7] On this basis, many researchers utilized the pre-reconstruction of electrocatalysts to obtain a large number of active species for the catalytic reactions. [8] It has been found that the intrinsic properties of the pre-catalysts, such as composition, atomic arrangement, porosity, and crystallinity, would affect the reconstruction rate, reconstruction degree, and catalytic activity of the reconstructed species. [9] Moreover, the reaction conditions also affect the reconstruction process, such as electrochemical operation, applied potential, electrolyte concentration, and pH. [6a] Therefore, tuning the reconstruction process to generate abundant active sites with high intrinsic activity is an effective strategy to boost the catalytic performance of electrocatalysts.Although some influential review articles on the reconstruction of catalysts during water electrolysis have emerged, [10] most of them focus on the discovery and characterization of the reconstruction phenomenon, less on the regulation of the reconstruction process. In addition, reconstructed catalysts for Water electrolysis is regarded as an efficient and green method to produce hydrogen gas, a clean energy carrier that holds the key to solving global energy problems. So far, the efficiency and large-scale application of water electrolysis are restricted by the electrocatalytic activity of applied catalysts. Recently, the reconstruction phenomenon of electrocatalysts during a catalytic reaction has been discovered, which ...

CoP/Fe‐Co9S8 for Highly Efficient Overall Water Splitting with Surface Reconstruction and Self‐Termination

“…The conjugation of different reconstruction strategies, such as surface activation, heterostructure construction, defect engineering, ionic doping, partial dissolution, and deep reconstruction, may lead to a more active catalytic surface. [ 24 , 25 ] On the other hand, excessive reconstruction may destroy the structural stability of the catalysts due to the serious dissolution of components, resulting in the loss of catalysts’ stability. [ 26 ] Therefore, the depth of reconstruction should be tuned to inhibit the dissolution of active species and eventually obtain an OER catalytic interface with efficiency and stability.…”

A Mini Review on Transition Metal Chalcogenides for Electrocatalytic Water Splitting: Bridging Material Design and Practical Application

“…The two important unresolved questions for TMCs as OER electrocatalysts are how the surface reconstructs during the OER and how the TMCs affect the activity/stability of the actual active sites. 163 Although there is no consensus on these open questions yet, many works in recent literature attempted to unveil the underpinning mechanism from different case studies. 164 For example, chalcogenides transformed from LDHs are recently reported showing high performance of OER 165,166 Xu et al 15 reported an iron-doped TMDs (Ni x Fe 1−x Se 2 ) derived from corresponding LDHs with edge active sites for OER.…”

“…The two important unresolved questions for TMCs as OER electrocatalysts are how the surface reconstructs during the OER and how the TMCs affect the activity/stability of the actual active sites . Although there is no consensus on these open questions yet, many works in recent literature attempted to unveil the underpinning mechanism from different case studies .…”

A dual-strategy of interface and reconstruction engineering to boost efficient alkaline water and seawater oxidation

“…[25][26][27][28][29][30][31] This in situ reconstruction process could adjust the electrocatalytic behaviors and thus improve the catalytic performance. 32 For instance, Dai and co-workers reported an outstanding hierarchical anode catalyst consisting of a nickel-iron hydroxide layer coated on a nickel sulde layer that affords superior catalytic activity and corrosion resistance in alkaline seawater electrolysis. 33 Note that the in situ generated polyanion-rich passivating layers are responsible for high corrosion resistance.…”