Dual-Terminal Engineering of Nanorod Heterojunctions Enables Charge-Proton Balanced Photocatalytic H ₂ Evolution Coupled with Imine Production

Light-driven conversion of primary amines to imines and H 2 offers a compelling carbon-neutral route to the co-production of high-value fine chemicals and clean fuels, yet its efficiency remains constrained by an asymmetric imbalance in the supply and consumption of charges and protons. Here, we present a dual-terminal engineering strategy for heterojunction photocatalysts that circumvents this challenge by concurrently modulating CdS nanorod length at the oxidation terminus for C−N coupling of benzylamine (BA) into N -benzylidenebenzylamine (BBA), while tailoring Ag species at the reduction terminus for H 2 generation. Spectroscopic and theoretical investigations untangle that elongating the nanorod length enhances intrinsic electron-hole separation within CdS and promotes interfacial electron transfer from CdS to the Ag species, whereas distinct Ag species (Ag and Ag 2 S) exhibit markedly different electron-trapping and H 2 -evolution capabilities. Specifically, the faster electron acceptance yet slower H 2 evolution kinetics of Ag drive the accumulation of unconsumed electrons and protons, which are diverted toward BBA hydrogenation to secondary amines—simultaneously retarding further BA dehydrogenation and accelerating CdS photocorrosion through the buildup of unreacted holes. Conversely, Ag 2 S achieves kinetic harmony between electron trapping and H 2 evolution, effectively suppressing both parasitic reactions and photocorrosion. Consequently, Ag 2 S/CdS nanorods of optimal length deliver near-stoichiometric and long-sustained co-evolution of BBA and H 2 at outputs of 38.9 and 35.0 mmol g cat −1 h −1, together with 100% BBA selectivity. This work opens a generalizable avenue for orchestrating charge and proton equilibrium in heterojunction photocatalysts toward efficient and selective redox transformations.