Direct generation of nitrogen-centered radicals via non-covalent interaction between Cu complexes and BiVO₄ photoanodes.

Abstract

Semiconductor-based photoelectrochemistry commonly relies on efficient interactions between semiconductor surfaces and adsorbates for promoting charge transfer and efficiently activating inert bonds. But at the repulsive interfaces (e.g., between like-charged substrates and electrodes), such interactions cannot be achieved. Contrary to this paradigm, we find that the van der Waals interaction between a series of N-coordinated Cu complex cations and BiVO₄ photoanodes results in a high photovoltage of 0.53 V and charge transfer efficiency of 96%, along with the photocurrent density approaching the theoretical limit of BiVO₄. This non-covalent interaction enables the universal generation of nitrogen-centered radicals from directly cleaving native N-H bonds and generates N-N coupling products with a Faradaic efficiency exceeding 96%. Its practical application is further demonstrated in an amplified photoelectrochemical reactor, generating a photocurrent of 409 mA and a yield rate of 6069 μmol h^-1 for hydrazine production, which is competitive with most reported N-N coupling methods.