Atomically Dispersed d10 s-block Au Boosts Photocatalytic 1e- Water Oxidation for Self-Cleaning, Sanitation and Safe Drinkable Water­­ (preprint)

ABSTRACT

Providing affordable safe drinking water and universal sanitation poses a grand challenge especially after the global COVID-19 pandemic. In this work, we developed atomically dispersed Au on potassium-incorporated polymeric carbon nitride (AuKPCN) that could simultaneously boost photocatalytic generation of ·OH and H2O2 with an apparent quantum efficiency over 90% at 400–420 nm. The introduction of potassium into the poly(heptazine imide) matrix formed strong K-N bonds, preventing Au from forming strong interactions with N. Instead, Au formed a bond with C, only having weak interactions with N on KPCN, which rendered Au with an oxidation number close to 0. The results of in-situ vibrational spectroscopy, isotopic experiments, transient absorption spectroscopy and time-dependent density functional theory (TDDFT) simulations revealed that the low-valent Au could append its 6s orbital into the band diagram of AuKPCN that formed a trapping level for generating highly localized holes under photoexcitation. These highly localized holes could boost the 1e− water oxidation reaction to form highly oxidative ·OH and simultaneously unbind the hydrogen atom in H2O molecule, which greatly promoted the hydrogenation process during the 2e− oxygen reduction reaction (ORR) to produce H2O2. The photogenerated ·OH on AuKPCN led to a more than 120-fold efficiency enhancement for visible-light-response superhydrophilicity as compared to that of the commercial TiO2. The onsite fixed-bed reactor under photo-illumination achieved a remarkable 132.5 LH2O m− 2 day− 1 water disinfection rate (lg6), which is about 30 times superior than the TiO2 photocatalytic advanced oxidation process in the most ideal case (< 4 LH2O m− 2 day− 1; lg4).