Redox cocatalysts play crucial roles in photosynthetic reactions, yet simultaneous loading of oxidative and reductive cocatalysts often leads to enhanced charge recombination that is detrimental to photosynthesis. This study introduces an approach to simultaneously load two redox cocatalysts, atomically dispersed cobalt for improving oxidation activity and anthraquinone for improving reduction selectivity, onto graphitic carbon nitride (C3N4) nanosheets for photocatalytic H2O2production. Spatial separation of oxidative and reductive cocatalysts was achieved on a two-dimensional (2D) photocatalyst, by coordinating cobalt single atom above the void center of C3N4and anchoring anthraquinone at the edges of C3N4nanosheets. Such spatial separation, experimentally confirmed and computationally simulated, was found to be critical for enhancing surface charge separation and achieving efficient H2O2production. This center/edge strategy for spatial separation of cocatalysts may be applied on other 2D photocatalysts that are increasingly studied in photosynthetic reactions.

Heme-copper oxidase (HCO) catalyzes the natural reduction of oxygen to water using a heme-copper center. Despite decades of research on HCO's, the role of nonheme metal and Nature's choice of copper over other metals like iron remains unclear. Here, we use a biosynthetic model of HCO in myoglobin that selectively binds different nonheme metals to demonstrate 30-fold and 11-fold enhancements in oxidase activity of Cu- and Fe-bound HCO mimics respectively, as compared to Zn-bound mimics. Detailed electrochemical, kinetic and vibrational spectroscopic studies, in tandem with theoretical DFT calculations demonstrate that the nonheme metal not only donates electrons to oxygen but also activates it for efficient O-O bond cleavage. Furthermore, the higher redox potential of copper and the enhanced weakening of O-O bond from the higher electron density in the d-orbital of copper are central to its higher oxidase activity over iron. This work resolves a long-standing question in bioenergetics, and renders a chemical-biological basis for designing future oxygen reduction catalysts.

This study presents a single-atom Pt catalyst that achieves efficient C–F bond activation, which is a challenging reaction in both chemical synthesis and environmental remediation of recalcitrant fluorinated hydrocarbons. Up to 1.6 wt % Pt was loaded as a single-atom on SiC substrate (Pt1/SiC) using a facile, scalable wet-chemical method developed based on anchor-site and photoreduction techniques. The high catalytic activity of Pt1/SiC for hydrodefluorination of perfluorooctanoic acid, which is a select perfluorinated pollutant of significant environmental concern, is attributed to the effective hydrogen spillover from isolated Pt onto the SiC surface where the resulting Si–H bond further redistributes with the C–F bond to accomplish hydrodefluorination.

We here present an innovative approach to increase the electron density of metallic Pd nanoparticles loaded on TiO2 photocatalysts by coordinating Pd with surface-anchored organic ligands. X-ray photoelectron spectroscopy and X-ray absorption near edge structure measurements confirm the negative charge on the Pd nanoparticle induced by electron donation from amine groups of the ligands. The electronically modified Pd on TiO2 exhibits unprecedentedly high photocatalytic H2O2 production from O2 reduction. Mechanistic investigations suggest that the enhanced performance results from electronic tuning of Pd nanoparticles, leading to enhanced charge separation on the TiO2 support, improved activity of Pd nanoparticles as an oxygen reduction center, and improved selectivity for O2 reduction to produce H2O2.

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