To realize future carbon neutrality, clean and sustainable electrochemical energy conversion and storage technologies are indispensable. Current devices include rechargeable batteries (e.g., Li-ion, Na-ion, and K-ion battery), fuel cells, and supercapacitors (SCs) that hold crucial positions in solving the current energy crisis and environmental pollution issues. [1][2][3][4] SCs and rechargeable batteries are the most popular electrochemical energy storage devices meeting future energy development demands. SCs usually possess high-power densities and long cycling lives but still suffer from low-energy densities. By comparison, rechargeable batteries have high-energy densities but still limited by lowpower densities, poor cycling stabilities, and short cyclic lives. Such tremendous differences in electrochemical properties between SCs and rechargeable batteries mainly originate from the differences in charge storage mechanisms. [5] According to the different charge storage mechanisms, SCs can be classified into electric double-layer capacitors (EDLCs), pseudocapacitors, and hybrid capacitors. [6,7] SCs made of carbon materials, such as carbon-based EDLCs, store electric charges at the electrode and electrolyte interface via physical adsorption/desorption of electrolyte ions. This process only involves surface reactions of ions without ion diffusion within the bulk electrode materials. [7][8][9] Pseudocapacitance often involves a Faradaic charge storage process by fast and highly reversible surface or near-surface redox reactions. Typically, pseudocapacitive electrode could be distinguished in underpotential deposition, redox reactions of transition metal oxides, and intercalation pseudocapacitance. [7] In most cases, functionalized porous carbons, such as oxygen-containing functional groups or heteroatomdoped carbon materials, have both EDL capacitance and pseudocapacitive storage mechanisms. Hybrid capacitors combine the advantages of EDLCs and pseudocapacitors, in which one electrode stores electric charge through battery-type faradaic process, while the other electrode stores electric charge based on capacitive mechanism. [10,11] Rechargeable batteries, such as Li-ion batteries (LIBs) and post-LIBs based on different charge carriers such as Na + and K + , store electric charges through intercalation, deintercalation, or adsorption of ions between the anode and cathode during charge/discharge processes. [1] For electrocatalysis, processes such as oxygen reduction reaction (ORR) in fuel cells and hydrogen evolution reaction (HER), as well as oxygen evolution reaction (OER) in water splitting, N 2 reduction reaction (NRR) and CO 2 reduction reaction (CO 2 RR), all often require high overpotentials and manifest sluggish kinetics in the absence of catalysts. The electrocatalytic processes usually take place according to three critical steps: 1) mass diffusion; 2) electron transfer; and 3) surface or interface reactions. [12] Generally, electrocatalytic ORR is a three-phase reaction and mainly includes two pathways:...
