A p‑n‑p Configuration Based on the Cuprous Oxide/Silicon Tandem Photocathode for Accelerating Solar-Driven Hydrogen Evolution

Photoelectrochemical splitting of water into hydrogen is a potential route to motivate the application of solar-driven conversion to clean energy but is regularly limited by its low efficiency. The key to addressing this issue is to design a suitable photocathode configuration for high-efficiency photogenerated carrier separation and transmission to photocathode-surface reaction sites. In this work, we report a Si-Cu2O tandem photocathode featuring a p-n-p configuration for solar-driven hydrogen evolution in an alkaline solution. Driven by this built-in field, the electrons induced from Si were transferred through FeOOH, which acted as electron tunnels, to combine with the holes from Cu2O, triggering more electrons generated from Cu2O to particiate in the surface reaction. Under simulated sunlight, the optimized photocathode achieved and maintained a photocurrent density of −11 mA/cm2 at 0 VRHE in alkaline conditions for 120 min, outperforming the reported tandem cell consisting of Si and Cu2O photocathodes. Our results provide valuable insight into a feasible way to construct an optimized photocathode for efficient solar-driven H2 evolution

Composite of Hierarchically Porous N‑Doped Carbon/Carbon Nanotube with Greatly Improved Catalytic Performance for Oxygen Reduction Reaction

In this work, a series of catalysts were synthesized by pyrolysis of in situ formed hybrids of metal–organic framework MIL-101­(Fe) and polypyrrole (PPy) nanotube followed by acid etching. The obtained catalysts exhibit composite structure of hierarchically porous carbon and carbon nanotube, which endowed the catalysts high surface areas, plenty of active sites and high conductivity, and thus high electrocatalytic performance on oxygen reduction reaction (ORR). The optimum onset and half-wave potential of +17 and −116 mV (vs Ag/AgCl) have been obtained, respectively, which is even 4 and 12 mV positive than commercial Pt/C (20%) in alkaline. The catalyst also exhibits superior long-term stability and durability against methanol. Kinetic investigations have shown that ORR on the catalyst tended to a more effective 4e^– dominant transfer process, which makes it a promising nonprecious metal ORR catalyst for fuel cell