Ultrafine PtCo alloy by pyrolysis etching-confined pyrolysis for enhanced hydrogen evolution.

Zeolitic imidazolate framework-67 (ZIF-67) has been widely used as a precursor to developing efficient PtCo alloy catalysts for hydrogen evolution reaction (HER). However, traditional in-situ pyrolysis strategies involve complicated interface structure modulating processes between ZIF-67 and Pt precursors, challenging large-scale synthesis. Herein, a "pyrolysis etching-confined pyrolysis" approach is developed to design confined PtCo alloy in porous frameworks of onion carbon derived from ZIF-67. The confined PtCo alloy with Pt content of only 5.39 wt% exhibits a distinct HER activity in both acid (η10: 5 mV and Tafel: 9 mV dec-1) and basic (η10: 33 mV and Tafel: 51 mV dec-1) media and a drastic enhancement in stability. Density functional theory calculations reveal that the strong electronic interaction between Pt and Co allows favorable electron redistribution, which affords a favorable hydrogen spillover on PtCo alloy compared with that of pristine Pt(111). Operational electrochemical impedance spectroscopy demonstrates that the Faraday reaction process is facilitated under acidic conditions, while the transfer of intermediates through the electric double-layer region under alkaline conditions is accelerated. This work not only offers a universal route for high-performance Pt-based alloy catalysts with metal-organic framework (MOF) precursors but also provides experimental evidence for the role of the electric double layer in electrocatalysis reactions.

[Comparison of ultrasound-guided transrectal and transperineal prostate biopsies in clinical application].

OBJECTIVE: To compare the positive rates and complications of ultrasound-guided transrectal and transperineal prostate biopsies. METHODS: We retrospectively analyzed 156 cases of ultrasound-guided transrectal (n = 97) and transperineal (n = 59) prostate biopsy, and compared the positive rate and post-biopsy complications between the two approaches. RESULTS: The positive rates in the transrectal and transperineal groups were 48.4% and 44.1%, respectively, with no significant difference between the two approaches according to different PSA levels (P >0.05). No statistically significant differences were observed between the transrectal and transperineal groups in the post-biopsy incidence rates of such complications as hematuria (54.6% vs 42.4%, P >0.05), lower urinary tract symptoms (17.5% vs 22.0%, P >0.05), dysuria (9.3% vs 6.8%, P >0.05), and acute urinary retention (7.2% vs 6.8%, P >0.05). However, the incidence rates of post-biopsy infection and rectal bleeding were remarkably higher (15.5% vs 3.4%, P<0.05 and 50.5% vs 3.4%, P >0.01) while that of perineal swelling markedly lower in the former than in the latter (3.1% vs 13.6%, P <0.05). CONCLUSION: Transrectal and transperineal biopsies are both effective for the diagnosis of prostate cancer. Since their complications vary, the choice between the two methods depends on the specific condition of the patient.