Recent progress in atomically precise metal nanoclusters for photocatalytic application.

Photocatalysis is a widely recognized green and sustainable technology that can harness inexhaustible solar energy to carry out chemical reactions, offering the opportunity to mitigate environmental issues and the energy crisis. Photocatalysts with wide spectral response and rapid charge transfer capability are crucial for highly efficient photocatalytic activity. Atomically precise metal nanoclusters (NCs), an emerging atomic-level material, have attracted great interests owing to their ultrasmall size, unique atomic stacking, abundant surface active sites, and quantum confinement effect. In particular, the molecule-like discrete electronic energy level endows them with small-band-gap semiconductor behavior, which allows for photoexcitation in order to generate electrons and holes to participate in the photoredox reaction. In addition, metal NCs exhibit strong light-harvesting ability in the wide spectral UV-near IR region, and the diversity of optical absorption properties can be precisely regulated by the composition and structure. These merits make metal NCs ideal candidates for photocatalysis. In this review, the recent advances in atomically-precise metal NCs for photocatalytic application are summarized, including photocatalytic water splitting, CO2 reduction, organic transformation, photoelectrocatalytic reactions, N2 fixation and H2O2 production. In addition, the strategy for promoting photostability, charge transfer and separation efficiency of metal NCs is highlighted. Finally, a perspective on the challenges and opportunities for NCs-based photocatalysts is provided.

Holocene climatic controls on flooding regime along the Ussuri River in Northeast Asia.

Knowledge of the long-term flooding response to climatic changes is critical for probing the flooding future in an oncoming warmer world. In this paper, three well-dated wetland sedimentary cores with high-resolution grain-size records were employed to reconstruct the historical flooding regime along the Ussuri River during the past 7000 years. The results show that five flooding-prone intervals marked by increased mean rates of sand-fraction accumulation occurred at 6.4-5.9 ka BP, 5.5-5.1 ka BP, 4.6-3.1 ka BP, 2.3-1.8 ka BP, and 0.5-0 ka BP, respectively. These intervals are generally consistent with the higher mean annual precipitation controlled by the strengthened East Asian summer monsoon which has been widely documented in geological records across the monsoonal regions of East Asia. Considering the prevalent monsoonal climate along the modern Ussuri River, we suggest that the regional flooding evolution during the Holocene Epoch should be generally controlled by the East Asian summer monsoon circulation which was initially linked to the ENSO activities in the tropical Pacific Ocean. While for the last interval spanning 0.5-0 ka BP, human influence, compared with the long-serving climatic controls, has played a more critical role in driving the regional flooding regime.