Fe1-xNix(PO3)2/Ni2P Heterostructure for Boosting Alkaline Oxygen Evolution Reaction in Fresh Water and Real Seawater at High Current Density.

Oxygen evolution reaction (OER) is a limiting reaction for highly efficient water electrolysis. Thus, the development of cost-effective and highly efficient OER catalysts is the key to large-scale water electrolysis for hydrogen production. Herein, by using an interfacial engineering strategy, a unique nanoflower-like Fe1-xNix(PO3)2/Ni2P/NF heterostructure with abundant heterogeneous interfaces is successfully fabricated. The catalyst exhibits excellent OER catalytic activity in alkaline fresh water and alkaline natural seawater at high current densities, which only, respectively, requires overpotentials of 318 and 367 mV to drive 1000 mA cm-2 in fresh water and natural seawater both containing 1 M KOH. Furthermore, Fe1-xNix(PO3)2/Ni2P/NF demonstrates excellent durability, which can basically remain stable for 80 h during the electrocatalytic OER processes, respectively, in alkaline fresh water and natural seawater. This work provides a new construction strategy for designing highly efficient electrocatalysts for OER at high current densities both in alkaline fresh water and in natural seawater.

Endoscopic management of delayed bleeding after polypectomy of small colorectal polyps: two or more clips may be safe.

Background: The resection of small colorectal polyps (≤10 mm) is routine for endoscopists. However, the management of one of its main complications, namely delayed (within 14 days) postpolypectomy bleeding (DPPB), has not been clearly demonstrated. We aimed to assess the role of coloscopy in the management of DPPB from small colorectal polyps and identify the associated factors for initial hemostatic success. Methods: We conducted a retrospective study of 69 patients who developed DPPB after the removal of colorectal polyps of ≤10 mm and underwent hemostatic colonoscopy at the Sixth Affiliated Hospital of Sun Yat-sen University (Guangzhou, China) between April 2013 and June 2021. Demographics, clinical variables, and colonoscopic features were collected independently. We applied univariate and multivariate analyses to assess factors associated with initial hemostatic success. Results: General colonoscopy without oral bowel preparation was successfully performed in all the patients, with a median duration of 23.9 (12.5-37.9) minutes. Among 69 patients, 62 (89.9%) achieved hemostasis after initial hemostatic colonoscopy and 7 (10.1%) rebled 2.7 ± 1.1 days after initial colonoscopic hemostasis and had rebleeding successfully controlled by one additional colonoscopy. No colonoscopy-related adverse events occurred. Multivariate analysis showed that management with at least two clips was the only independent prognostic factor for initial hemostatic success (odds ratio, 0.17; 95% confidence interval, 0.03-0.91; P = 0.04). All the patients who had at least two clips placed at the initial hemostatic colonoscopy required no further hemostatic intervention. Conclusions: Colonoscopy is a safe, effective, and not too time-consuming approach for the management of patients with DPPB of small colorectal polyps and management with the placement of at least two hemoclips may be beneficial.