1e:T4b3,Exploiting noble-metal-free cocatalysts is of huge interest for photocatalytic water splitting using solar energy. Here we report a composite material consisting of CdS nanocrystals grown on the suface of a nanosized MoS2/graphene hybrid as a high-performance noble-metal-free photocatalyst for H2 evolution under visible light irradiation. Through the optimizing of each component proportion, the MoS2/G-CdS composite showed the highest photocatalytic H2 production activity when the content of the MoS2/graphene cocatalyst is 2.0 wt % and the molar ratio of MoS2 to graphene is 1:2. The photocatalytic H2 evolution activity of the proposed MoS2/G-CdS composite was tested and compared in Na2S-Na2SO3 solution and lactic acid solution. A 1.8 mmol/h H2 evolution rate in lactic acid solution corresponding to an AQE of 28.1% at 420 nm is not only higher than the case in Na2S-Na2SO3 solution of 1.2 mmol/h but also much higher than that of Pt/CdS in lactic acid solution. The relative mechanism has been investigated. It is believed that this kind of MoS2/G-CdS composite would have great potential as a promising photocatalyst with high efficiency and low cost for photocatalytic H2 evolution reaction.1f:T45b,Transition metal (TM)-based bimetallic spinel oxides can efficiently activate peroxymonosulfate (PMS) presumably attributed to enhanced electron transfer between TMs, but the existing model cannot fully explain the efficient TM redox cycling. Here, we discover a critical role of TM-O covalency in governing the intrinsic catalytic activity of Co_3-x Mn_x O₄ spinel oxides. Experimental and theoretical analysis reveals that the Co sites significantly raises the Mn valence and enlarges Mn-O covalency in octahedral configuration, thereby lowering the charge transfer energy to favor Mn_Oh -PMS interaction. With appropriate Mn^IV /Mn^III ratio to balance PMS adsorption and Mn^IV reduction, the Co_1.1 Mn_1.9 O₄ exhibits remarkable catalytic activities for PMS activation and pollutant degradation, outperforming all the reported TM spinel oxides. The improved understandings on the origins of spinel oxides activity for PMS activation may inspire the development of more active and robust metal oxide catalysts.20:T42b,We synthesized a series of carbon-supported atomic metal-N-C catalysts (M-SACs: M=Mn, Fe, Co, Ni, Cu) with similar structural and physicochemical properties to uncover their catalytic activity trends and mechanisms. The peroxymonosulfate (PMS) catalytic activity trends are Fe-SAC>Co-SAC>Mn-SAC>Ni-SAC>Cu-SAC, and Fe-SAC displays the best single-site kinetic value (1.65×10⁵ min^-1 mol^-1 ) compared to the other metal-N-C species. First-principles calculations indicate that the most reasonable reaction pathway for ¹ O₂ production is PMS→OH*→O*→¹ O₂ ; M-SACs that exhibit moderate and near-average Gibbs free energies in each reaction step have a better catalytic activity, which is the key for the outstanding performance of Fe-SACs. This study gives the atomic-scale understanding of fundamental catalytic trends and mechanisms of PMS-assisted reactive oxygen species production via M-SACs, thus providing guidance for developing M-SACs for catalytic organic pollutant degradation.21:T5c5,

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