||The nucleophile oxidation reaction (NOR) is of enormous significance for organic electrosynthesis and coupling for hydrogen generation. However, the nonuniform NOR mechanism limits its development. For the NOR, involving electrocatalysis and organic chemistry, both the electrochemical step and non-electrochemical process should be taken into account. The NOR of nickel-based hydroxides includes the electrogenerated dehydrogenation of the Ni2+–OH bond and a spontaneous non-electrochemical process; the former determines the electrochemical activity, and the nucleophile oxidation pathway depends on the latter. Herein, the space-confinement-induced synthesis of Ni3Fe layered double hydroxide intercalated with single-atom-layer Pt nanosheets (Ni3Fe LDH-Pt NS) is reported. The synergy of interlayer Pt nanosheets and multiple defects activates Ni–OH bonds, thus exhibiting an excellent NOR performance. The spontaneous non-electrochemical steps of the NOR are revealed, such as proton-coupled electron transfer (PCET; Ni3+–O + X–H = Ni2+–OH + X•), hydration, and rearrangement. Hence, the reaction pathway of the NOR is deciphered, which not only helps to perfect the NOR mechanism, but also provides inspiration for organic electrosynthesis.