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Hydrogen peroxide was produced as a solar fuel from water and dioxygen using solar energy by combination of a water oxidation catalyst and a photocatalyst for two-electron reduction of O 2 in acidic aqueous solutions. Photocatalytic production of H 2 O 2 occurred under photoirradiation of [Ru II (Me 2 phen) 3 ] 2+ (Me 2 phen ¼ 4,7-dimethyl-1,10-phenanthroline) used as a photocatalyst with visible light in the presence of Ir(OH) 3 acting as a water oxidation catalyst in an O 2-saturated H 2 SO 4 aqueous solution. Photoinduced electron transfer from the excited state of [Ru II (Me 2 phen) 3 ] 2+ to O 2 results in the formation of [Ru III (Me 2 phen) 3 ] 3+ and a superoxide radical anion (O 2 _ À) which is protonated to produce H 2 O 2 via disproportionation of HO 2 _ in competition with back electron transfer (BET) from O 2 _ À to [Ru III (Me 2 phen) 3 ] 3+. [Ru III (Me 2 phen) 3 ] 3+ oxidises water with the aid of catalysis of Ir(OH) 3 to produce O 2. The photocatalytic reactivity of H 2 O 2 production was improved by replacing Ir(OH) 3 nanoparticles by [Co III (Cp*)(bpy)(H 2 O)] 2+ in the presence of Sc(NO 3) 3 in water. The optimised quantum yield of the photocatalytic H 2 O 2 production at l ¼ 450 nm was determined using a ferrioxalate actinometer to be 37%. The value of conversion efficiency from solar energy to chemical energy was also determined to be 0.25%. Broader context Photocatalytic production of hydrogen peroxide from earth-abundant water and dioxygen using solar energy as an ideally sustainable solar fuel has remained a great challenge. We report herein for the rst time photocatalytic production of hydrogen peroxide from water and dioxygen under visible light using [Ru II (Me 2 phen) 3 ] 2+ (Me 2 phen ¼ 4,7-dimethyl-1,10-phenanthroline) as a photocatalyst and Ir(OH) 3 nanoparticles or [Co III (Cp*)(bpy)(H 2 O)] 2+ (Cp* ¼ h 5-pentamethylcyclopentadienyl, bpy ¼ 2,2-bipyridine) as a water oxidation catalyst in water containing H 2 SO 4 or Sc(NO 3) 3. A high turnover number and quantum yield have been attained by combining an efficient water oxidation catalyst with a photosensitiser and a Lewis acid in water.

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Uremic toxins often accumulate in patients with compromised kidney function, like those with chronic kidney disease (CKD), leading to major clinical complications including serious illness and death. Sufficient removal of these toxins from the blood increases the efficacy of hemodialysis, as well as the survival rate, in CKD patients. Understanding the interactions between an adsorbent and the uremic toxins is critical for designing effective materials to remove these toxic compounds. Herein, we study the adsorption behavior of the uremic toxins, p-cresyl sulfate, indoxyl sulfate, and hippuric acid, in a series of zirconium-based metal−organic frameworks (MOFs). The pyrene-based MOF, NU-1000, offers the highest toxin removal efficiency of all the MOFs in this study. Other Zr-based MOFs possessing comparable surface areas and pore sizes to NU-1000 while lacking an extended aromatic system have much lower toxin removal efficiency. From single-crystal X-ray diffraction analyses assisted by density functional theory calculations, we determined that the high adsorption capacity of NU-1000 can be attributed to the highly hydrophobic adsorption sites sandwiched by two pyrene linkers and the hydroxyls and water molecules on the Zr 6 nodes, which are capable of hydrogen bonding with polar functional groups of guest molecules. Further, NU-1000 almost completely removes p-cresyl sulfate from human serum albumin, a protein that these uremic toxins bind to in the body. These results offer design principles for potential MOFs candidates for uremic toxin removal.