Recent Advances and Performance Enhancement Mechanisms of Pulsed Electrocatalysis

Due to the excessive exploitation and utilization of fossil fuels, we are faced with severe energy and environmental problems.Therefore, it's significant to develop electrocatalytic energy conversion, chemical synthesis and pollutant degradation technologies.In order to achieve high activity, selectivity and stability of electrocatalytic reactions, researchers have made a lot of efforts in catalyst design, interface microenvironment regulation and reactor structure optimization.In fact, there is still a wide space on the power supply side for the regulation of electrocatalytic system.Although most researchers choose to use potentiostatic or galvanostatic power supply strategy, some studies have proven that the pulsed power supply strategy by implementing altering potential periodically can improve electrocatalytic performance to a great extent.Compared with traditional regulating methods mentioned above, the pulsed electrocatalysis is much simpler, efficient and repeatable because it just needs to modulate the output potential or current mode.In addition, it is more favorable to be coupled with smart energy in the future.Therefore, the pulsed electrocatalysis has broad development prospects.In this review, we summarized the application and recent progress of the pulsed power supply strategy in classical electrocatalytic systems include electrochemical advanced oxidation processes, electrochemical carbon dioxide reduction, organic electrochemical synthesis, hydrogen production through water electrolysis.Besides, we analyzed the enhancement mechanisms of pulsed electrocatalysis.These enhancement mechanisms can be generalized as follows: (1) By updating the concentration of substance in Nernst diffusion layer during the implementation of switching potential periodically, the concentration polarization can be prevented.Thus, the electrocatalytic activity can be enhanced.Besides, some side reactions caused by mass transfer restriction can also be suppressed.(2) Through altering the adsorption energy of the reaction intermediate and adjusting the coverage of intermediate on the catalyst surface under oscillating potential periodically, the electrocatalytic selectivity of target reaction can be increased.Furthermore, because the active site of catalyst can be modulated to alternate between ideal states for adsorption of intermediate and desorption of product, the Sabatier's theoretical limit on static catalytic site may be breached and the turnover frequency (TOF) of the catalyst can increase by several orders of magnitude during the pulsed dynamic electrocatalysis process.(3) The catalyst surface can be kept in a non-equilibrium state to avoid the inactivation caused by excessive oxidation or reduction of active site or the deposition of some toxic substances on the surface of a catalyst.Thus, the electrocatalytic stability will be improved.Besides, the dynamic reconfiguration of catalysts during pulsed electrocatalysis will influence the activity and selectivity of reaction.Finally, we prospect for the challenges and opportunities of pulsed electrocatalysis in the future.