Efficient molecular oxygen activation is crucial for catalytic oxidation reaction, but highly depends on the construction of active sites. In this study, we demonstrate that dual adjacent Fe atoms anchored on MnO2 can assemble into a diatomic site, also called as MnO2-hosted Fe dimer, which activates molecular oxygen to form an active intermediate species Fe(O = O)Fe for highly efficient CO oxidation. These adjacent single-atom Fe sites exhibit a stronger O2 activation performance than the conventional surface oxygen vacancy activation sites. This work sheds light on molecular oxygen activation mechanisms of transition metal oxides and provides an efficient pathway to activate molecular oxygen by constructing new active sites through single atom technology.

The objective of photocatalytic CO2 reduction (PCR) is to achieve high selectivity for a single energy‐bearing product with high efficiency and stability. The bulk configuration usually determines charge carrier kinetics, whereas surface atomic arrangement defines the PCR thermodynamic pathway. Concurrent engineering of bulk and surface structures is therefore crucial for achieving the goal of PCR. Herein, an ultrastable and highly selective PCR using homogeneously doped BiOCl nanosheets synthesized via an inventive molten strategy is presented. With B2O3 as both the molten salt and doping precursor, this new doping approach ensures boron (B) doping from the surface into the bulk with dual functionalities. Bulk B doping mitigates strong excitonic effects confined in 2D BiOCl by significantly reducing exciton binding energies, whereas surface‐doped B atoms reconstruct the BiOCl surface by extracting lattice hydroxyl groups, resulting in intimate B‐oxygen vacancy (B‐OV) associates. These exclusive B‐OV associates enable spontaneous CO2 activation, suppress competitive hydrogen evolution and promote the proton‐coupled electron transfer step by stabilizing *COOH for selective CO generation. As a result, the homogeneous B‐doped BiOCl nanosheets exhibit 98% selectivity for CO2‐to‐CO reduction under visible light, with an impressive rate of 83.64 µmol g−1 h−1 and ultrastability for long‐term testing of 120 h.

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Removal of non-biodegradable heavy metals has been the top priority in wastewater treatment and the development of green technologies remains asignificant challenge.W e demonstrate that phosphorylated nanoscale zero-valenti ron (nZVI) is promising for removal of heavy metals (Ni II ,C u II , Cr VI ,H g II )v ia ab oosted Kirkendall effect. Phosphorylation confines tensile hoop stress on the nZVI particles and "breaks" the structurally dense spherical nZVI to produce numerous radial nanocracks.E xemplified by Ni II removal, the radial nanocracks favor the facile inward diffusion of Ni II and the rapid outwardtransport of electrons and ferrous ions through the oxide shell for surface (Ni II /electron) and boundary (Ni II / Fe 0 )g alvanic exchange.A ccompanied by ap ronounced hollowing phenomenon, phosphorylated nZVI can instantly reduce and immobilizeN i II throughout the oxide shell with ah igh capacity (258 mg Ni g À1 Fe). Forr eal electroplating factory wastewater treatment, this novel nZVI performs simultaneous Ni II and Cu II removal, producing effluent of stable quality that meets local discharge regulations.

The efficiencies of semiconductor photocatalysis are always severely restricted by the rapid recombination of charge carriers in the bulk phase, while local polarization is an efficient scenario to conquer the above issue to boost the photocatalytic performance. Here, as a proof‐of‐concept demonstration, local charge polarization induced by the intrinsic zwitterionic resonance structure of photocatalysts is reported. A novel squaraine‐based covalent organic framework (SQ‐COF‐1) photocatalyst with an interesting zwitterionic resonance structure is creatively developed. Meanwhile, the comparison samples (SQ‐COF‐2 and PDA‐COF) based on similar COF structure with tunable local polarity are accordingly designed and prepared. The local charge polarization generated from the zwitterionic resonance structure profoundly redistributes and separates the charge carriers, as evidenced by experimental and theoretical results collectively. Benefiting by the largest local polarization, SQ‐COF‐1 exhibits superior visible‐light‐driven photocatalytic activities than SQ‐COF‐2, PDA‐COF, and commonly used polymeric carbon nitride photocatalyst. This work presents a local charge polarization protocol for engineering charge behavior to promote photocatalysis, which shows great promise for the future design of high‐performance photocatalytic materials.