Degradation of endoplasmic reticulum (ER) by selective autophagy (ER‐phagy) is crucial for ER homeostasis. However, it remains unclear how ER scission is regulated for subsequent autophagosomal sequestration and lysosomal degradation. Here, we show that oligomerization of ER‐phagy receptor FAM134B (also referred to as reticulophagy regulator 1 or RETREG1) through its reticulon‐homology domain is required for membrane fragmentation in vitro and ER‐phagy in vivo. Under ER‐stress conditions, activated CAMK2B phosphorylates the reticulon‐homology domain of FAM134B, which enhances FAM134B oligomerization and activity in membrane fragmentation to accommodate high demand for ER‐phagy. Unexpectedly, FAM134B G216R, a variant derived from a type II hereditary sensory and autonomic neuropathy (HSAN) patient, exhibits gain‐of‐function defects, such as hyperactive self‐association and membrane scission, which results in excessive ER‐phagy and sensory neuron death. Therefore, this study reveals a mechanism of ER membrane fragmentation in ER‐phagy, along with a signaling pathway in regulating ER turnover, and suggests a potential implication of excessive selective autophagy in human diseases.
Topological defects, with an asymmetric local electronic redistribution, are expected to locally tune the intrinsic catalytic activity of carbon materials. However, it is still challenging to deliberately create high‐density homogeneous topological defects in carbon networks due to the high formation energy. Toward this end, an efficient NH3 thermal‐treatment strategy is presented for thoroughly removing pyrrolic‐N and pyridinic‐N dopants from N‐enriched porous carbon particles, to create high‐density topological defects. The resultant topological defects are systematically investigated by near‐edge X‐ray absorption fine structure measurements and local density of states analysis, and the defect formation mechanism is revealed by reactive molecular dynamics simulations. Notably, the as‐prepared porous carbon materials possess an enhanced electrocatalytic CO2 reduction performance, yielding a current density of 2.84 mA cm−2 with Faradaic efficiency of 95.2% for CO generation. Such a result is among the best performances reported for metal‐free CO2 reduction electrocatalysts. Density functional theory calculations suggest that the edge pentagonal sites are the dominating active centers with the lowest free energy (ΔG) for CO2 reduction. This work not only presents deep insights for the defect engineering of carbon‐based materials but also improves the understanding of electrocatalytic CO2 reduction on carbon defects.
However, the CO 2 RR suffers from the competitive H 2 evolution process and the sluggish kinetics due to the chemical inertness of the CO 2 molecule, which diminishes the product selectivity and conversion efficiency. [2] Efficient electrocatalysts are therefore urgently demanded to accomplish the CO 2 RR at a low overpotential with high selectivity and large current density. [3] So far numerous electrocatalysts including metals, [4] metal oxides, [5] metal-organic frameworks, [6] molecular complexes, [7] and various carbon-based materials [8] have been developed to boost the CO 2 RR. Among which precious-metalbased catalysts (PMCs), for example, Au and Ag, exhibit the most efficient CO 2to-CO conversion particularly at low overpotentials. [9] However, the state-of-the-art PMCs suffer from their scarcity and high cost as well as the difficulty to achieve meaningful improvements in efficiency and selectivity at high current densities, limiting their practical application in the facet of the industry and therefore stimulating the exploration of low-cost catalysts composed of earth-abundant elements with attractive performance for the CO 2 RR. [10] Recently, transition metal-nitrogen-carbon (MNC) materials with atomically dispersed MN x active sites have been emerging as promising catalysts towards various reactions including oxygen reduction reaction (ORR), [11] hydrogen evolution reaction (HER), [12] and CO 2 RR [13] due not only to their combination in the merits of both heterogeneous and homogeneous catalysts but also their role in bridging the gap between these two kinds of catalysts with unique features. Among this series of materials, atomic NiNC catalysts exhibit impressive Faradaic Efficiency (FE) (> 80%) of CO formation in a wide voltage range (−0.4 to −1.0 V vs RHE) and represent one of the most promising low-cost catalysts towards CO 2 RR. [14] However, atomic NiNC catalysts still possess the drawback of unsatisfactory CO 2 RR kinetics. For example, although atomic NiNC catalysts display an onset potential as low as ca. 70 mV, even comparable with those of the state-of-the-art Au catalysts, the applied potential at CO partial current density (j CO ) of 10 mA cm −2 for these catalysts is usually more negative than −0.6 V versus RHE in an H-cell, inferior to the Au catalysts and far from satisfactory. [15] Herein, an active catalyst A-Ni@CMK is developed with the atomically dispersed NiN 4 moieties on the mesoporous carbon for the electrocatalytic CO 2 reduction reaction (CO 2 RR) through a step-by-step pore-filling synthetic strategy. Concretely, the as-synthesized catalyst A-Ni@CMK exhibits outstanding catalytic performance for CO 2 RR in the H-cell with a Faradaic efficiency of CO (FE CO ) > 80% in a wide electrochemical potential window (−0.5 to −0.9 V vs RHE) and a large CO partial current density (j CO ) of 24 and 51 mA cm −2 at −0.6 and −0.8 V versus RHE, respectively. Notably, j CO for A-Ni@ CMK can further reach the industrial-level values of 366 mA cm −2 at −0.8 V versus RHE, re...
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