Science Bulletin最新文献

Current strategies to enhance Zn reversibility in aqueous Zn batteries (AZBs) primarily focus on inducing planar deposition. However, electrodissolution, as the initial operational step in AZBs, significantly affects deposition behavior and reversibility, yet it is surprisingly overlooked. Herein, the crucial electrodissolution behavior of Zn electrodes and its impact on irreversibility are comprehensively elucidated. First, the dissolution pathways at different current densities are investigated at the microscopic level. As the current density increases, the electrodissolution behavior evolves from "point dissolution" to "line dissolution" and ultimately to "surface dissolution". Meanwhile, the proportion of dissolution area and depth changes at different operating protocols are quantitatively analyzed. Then, Combining theoretical calculations and experimental tests, dissolution differences among various crystal planes are unveiled with the sequence from weakest to toughest being (110), (101), (103), (102), (100), and (002). Additionally, morphological characterization and electrochemical-mass transport coupling models demonstrate that dissolution reshapes the surface morphology and interfacial microenvironment for deposition, which in turn determines nucleation and growth sites. More importantly, the mechanism of "dead Zn" formation is clarified by considering the internal structural heterogeneity of the dendrites and the external concentration distribution. As a proof of concept, Zn electrodes with preferred orientations constructed via epitaxial growth demonstrated uniform dissolution and achieved over a 46 % improvement in cycling lifespan compared to Zn electrodes with random orientations. This work provides a profound comprehension of the largely overlooked electrodissolution, opening a novel avenue for improving the reversibility of metal electrodes.

Climate change and the increasing frequency of floods have undermined China's food security. Creating detailed maps of flooded croplands is essential to improve prevention and adopt effective adaptation initiatives. Previous large-scale flood mapping efforts were hampered by limited meteorological and hydrological data, and the susceptibility of optical satellite images to cloud cover, leading to high uncertainty when downscaled to the cropland-scale. Here, using 4968 near-real-time (NRT) Sentinel-1 SAR (S1) images (spatial resolution: 10 m), we generated China's first set of high-resolution flooded cropland maps covering the period from 2017 to 2021. Our results demonstrate that croplands accounted for 43.8% to 49.8% of China's total flooded areas (ranging from 82,175 km² to 122,037 km²). We also created high-resolution flood maps specifically for rice and maize crops. The inundated rice areas ranged from 8428 km² to 22,123 km², accounting for 22.34% to 41.91% of the annual flooded croplands, or 2.82% to 7.45% of the annual rice cropland. In comparison, the inundated maize cropland fluctuated from 2619 km² to 5397 km², representing 5.38% to 13.56% of the annual flooded croplands. Our findings revealed extensive floods in rural areas, highlighting the urgent need to prioritize flood prevention and mitigation efforts in such regions. In light of China's allocation of an additional 1-trillion-RMB treasury bonds for water infrastructure projects, the high-resolution flood maps can be used to select sites for flood control projects, and evaluate the impact of flooding on crop yields and food security, thus targeting poverty alleviation in rural areas of China.

Elucidation of the dynamic evolution of active sites is still a challenge in investigating the catalytic mechanism mainly due to the difficulty in accurately detecting the transient structural changes of active sites under operating conditions. Here, we develop an advanced in situ electron paramagnetic resonance (EPR) spectroscopy, which could sensitively monitor and visualize the dynamic evolution of paramagnetic active sites during photoreduction CO₂. In situ results reveal that the photoactivated Cu¹⁺ sites from CuO nanoclusters/TiO₂ serve as the authentic active sites in the reaction and exhibit self-regenerative capability. The CO₂ molecules can acquire electrons and get activated by the photoactivated Cu¹⁺, leading to the transition of Cu¹⁺ sites into Cu²⁺ sites. Subsequently, the Cu²⁺ sites expedite the generation of hydrogen protons through antiferromagnetic coupling with hydroxyl radicals, thereby promoting the production of the final product CH₄ via a multi proton-coupled electron transfer (PCET) process. This work reveals and visualizes the dynamic evolution of Cu-based active sites during photocatalytic reactions by combined in situ characterizations, providing new perspectives on the mechanistic understanding of paramagnetic active sites under operation.