Electrochemical reduction of carbon dioxide (CO2) into chemicals and fuels has recently attracted much interest, but normally suffers from a high overpotential and low selectivity. In this work, single P atoms were introduced into a N‐doped carbon supported single Fe atom catalyst (Fe‐SAC/NPC) mainly in the form of P−C bonds for CO2 electroreduction to CO in an aqueous solution. This catalyst exhibited a CO Faradaic efficiency of ≈97 % at a low overpotential of 320 mV, and a Tafel slope of only 59 mV dec−1, comparable to state‐of‐the‐art gold catalysts. Experimental analysis combined with DFT calculations suggested that single P atom in high coordination shells (n≥3), in particular the third coordination shell of Fe center enhanced the electronic localization of Fe, which improved the stabilization of the key *COOH intermediate on Fe, leading to superior CO2 electrochemical reduction performance at low overpotentials.

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Developing efficient and stable electrocatalysts within a wide potential range is vital for the mature applications of the electrocatalytic CO 2 reduction reaction (CO 2 RR) into value-added chemical products. Herein, we engineered a NC@Ni/C nano-composite featuring a core−shell structure of a pyridinic-N-rich carbon layer encapsulating Ni nanoparticles (NPs) as a highly effective electrocatalyst for CO 2 RR to CO over a wide potential range. The catalyst demonstrates a high CO Faradaic efficiency (FE CO ) of >90% in a wide potential range from −0.65 to −1.45 V [vs reversible hydrogen electrode (RHE)] with the maximum FE CO of 97% at −1.05 V (vs RHE). Strikingly, it exhibits an excellent stability with a constant current density and a FE CO > 95% for 92 h at −1.05 V (vs RHE). Structural studies and DFT calculations further reveal that pyridinic-N doping in the carbon shell of Ni NPs plays a dual role in promoting the CO 2 RR activity. It not only alleviates the mass transfer limitation of CO 2 by enhancing the CO 2 adsorption capacity, but it also lowers the reaction energy barrier of the *COOH formation rate-determining step with the electronic structure modulation by Ni. This work may shed more light on the seeking of practical catalysts for high-efficiency electrochemical CO 2 reduction over a broad potential window.

The natural planar and rigid structures of most of the hydrophobic photosensitizers (PSs) [such as tetraphenyl porphyrin (TPP)] significantly reduce their loading efficiencies in polymeric nanoparticles (NPs) because of the strong π−π interaction-induced aggregation. This aggregation-caused quenching will further reduce the quantum yield of singlet oxygen ( 1 O 2 ) generation and weaken the efficiency of photodynamic therapy (PDT). In addition, the small molecular PSs exhibit short tumor retention time and tend to be easily cleared once released. Herein, poly(TPP) NPs, prepared by cross-linking of reactive oxygen species degradable, thioketal linkers and TPP derivatives, followed by coprecipitation, were first developed with quantitative loading efficiency (>99%), uniform NP sizes (without aggregation), increased singlet oxygen quantum yield (Φ Δ = 0.79 in dimethyl sulfoxide compared with 0.52 for original TPP), increased in vitro phototoxicity, extended tumor retention time, light-triggered on-demand release, and enhanced in vivo antitumor efficacy, which comprehensively address the multiple issues for most of the PSs in the PDT area.