Three-dimensional interconnected carbon nanoreactors with CoP nanocrystals to enhance performance in solar cells†

Failure to fully utilize the catalytic activity of electrode materials is a crucial bottleneck under the harsh operating conditions of a high concentration of iodine. Herein, we design an optimized counter electrode (CE) material with a large number of highly dispersed CoP ultrafine nanoparticles (∼10 nm in size) throughout P-doped multi-aperture honeycomb carbon as three-dimensional interconnected nanoreactors. The established 3D porous conductive honeycomb architecture offers a “highway” for accelerating charge and mass transfer, which facilitates the homogeneous distribution of infiltrated iodine and the close interaction between infiltrated iodine and CoP nanoparticles. This constructed structure not only provides a high surface-to-volume ratio to increase the number of exposed catalytic sites but also prevents nanoparticles from aggregating during cycling owing to the pore spatial confinement effect, ensuring the uniform dispersion of CoP, maximum catalytic effect and enhanced iodide ion diffusion. Additionally, the synergistic coupling effects between rich defect interfaces and chemical bonding derived from heteroatom-doping increase the catalytic activity. As a result, the developed CoP@PC catalyst presents superior power conversion efficiency (8.88%), outperforming all the known noble-metal Pt materials (7.82%). Such an unconventional material design offers an attractive and instructive model of high-performance nanomaterial engineering for application in various fields.